JUSTICE RARICK delivered the opinion of the court:

Claimant, Doris Ramirez, sought benefits pursuant to the Workers'Compensation Act (Act) (820 ILCS 305/1 et seq. (West 1996)) for injuries sustained whilein the employ of Concrete Structures of the Midwest, Inc., employer. The arbitrator foundclaimant sustained accidental injuries arising out of and in the course of her employment andawarded her 18 3/7 weeks temporary total disability and medical expenses of $2,178. Onreview, the Industrial Commission (Commission) affirmed the decision of the arbitrator, andthe circuit court of Cook County confirmed the decision of the Commission. Employerappeals contending the finding of causal connection between claimant's injuries and heremployment is against the manifest weight of the evidence. We affirm.

Claimant, a 26 year old carpenter, began working for employer November 6,1996. She had been employed as a carpenter since February 1993 for various othercompanies. While working for employer claimant was assigned the job of building concreteforms for the foundations of pumping houses. Such assignments required claimant tohammer, use a sledgehammer and wrench and cut wood with a contractor's saw. Claimantdescribed a contractor's saw as a longer and heavier circular saw which required the use ofboth hands in order to operate it. She testified gripping the saw required a lot of strengthand vibration went into both of her hands upon using the saw. On November 16, 1996,claimant noticed her hands were numb and she could not feel the fingertips. Claimant hadpreviously experienced occasional tingling sensations in both hands and fingers prior toworking for employer but such sensations went away after taking aspirin. Claimant lost notime from work because of her hands prior to November 16 nor did she have any medicaltreatment for them. This time the tingling and numbness continued on and off through theworkday. Claimant noted the tingling became more pronounced the harder the work. ByNovember 16, the pain was so intense claimant testified she could not sleep. Claimantsought treatment with Dr. Scott O'Conner on November 18, 1996. He found positive Phalenand Tinel signs bilaterally and diagnosed bilateral carpal tunnel syndrome. Claimant wasinstructed to remain off work. Dr. O'Conner opined claimant's employment with employerexacerbated a preexisting condition of carpal tunnel syndrome. Claimant was examinedagain on December 4, 1996, and was prescribed an EMG and surgery. The EMG revealedsevere carpal tunnel syndrome. Claimant was also examined by Dr. Michael Raymond whoconfirmed Dr. O'Conner's findings and opinions.

Employer's expert, Dr. Robert R. Schenck, saw claimant on April 11, 1997. According to the tests he administered, claimant was suffering from a mild to moderatebilateral carpal tunnel syndrome. He opined her carpal tunnel syndrome was an idiopathicpreexisting condition and was not related to, or aggravated by, her employment withemployer given claimant's history of prior tingling and the short duration of her employmentwith employer.

The Commission concluded claimant's carpal tunnel syndrome was aggravatedby her work for employer. The Commission therefore found that claimant sustainedaccidental injuries on November 16, 1996, which arose out of and in the course of heremployment.

It is well established that it is the function of the Commission to decidequestions of fact and causation, to judge the credibility of witnesses and to resolveconflicting medical evidence. See Mendota Township High School v. Industrial Comm'n,243 Ill. App. 3d 834, 836, 612 N.E.2d 77, 78 (1993); Dexheimer v. Industrial Comm'n, 202Ill. App. 3d 437, 442, 559 N.E.2d 1034, 1037 (1990). Though we might draw differentinferences from the evidence, we will not discard the findings of the Commission unlessthey are against the manifest weight of the evidence. See Mendota, 243 Ill. App. 3d at 836-37, 612 N.E.2d at 78; Dexheimer, 202 Ill. App. 3d at 443, 559 N.E.2d at 1037. In order fora finding to be contrary to the manifest weight of the evidence, an opposite conclusion mustclearly be apparent. See Illinois Bell Telephone Co. v. Industrial Comm'n, 265 Ill. App. 3d681, 687, 638 N.E.2d 307, 311 (1994). We cannot say an opposite conclusion is clearlyapparent in this instance. Claimant needed only to prove some act or phase of heremployment was a causative factor, not the sole or even principal causative factor, in herensuing injury to receive benefits under the Act. See Mendota, 243 Ill. App. 3d at 837, 612N.E.2d at 79; Three "D" Discount Store v. Industrial Comm'n, 198 Ill. App. 3d 43, 49, 556N.E.2d 261, 265 (1989). The fact that claimant may have had a preexisting condition doesnot preclude an award of benefits upon her showing her condition was aggravated oraccelerated by the employment. General Electric Co. v. Industrial Comm'n, 190 Ill. App.3d 847, 855, 546 N.E.2d 987, 992 (1989).

Claimant began working for employer on November 6. She was first assignedto build concrete forms for the foundation of a pumping station. In the course of buildingthe concrete forms, claimant was required to use repeatedly a contractor's saw and a hammer. Claimant described the contractor's saw as a longer, heavier circular saw which required theuse of both hands to operate it. She testified gripping the saw required a lot of strength andvibration went into both of her hands whenever she used it. Her next assignment alsoinvolved a lot of cutting and bolting concrete forms together. In order to perform the boltingclaimant testified she had to use two hands and apply pressure to tighten the nut. Her thirdassignment was constructing a platform. This task also required the use of the contractor'ssaw and hammering as well as the use of a sledgehammer to pound stakes into the ground. Her last job for employer was building concrete forms involving the same type of work sheperformed during her first assignment. During the course of performing her duties, claimantbegan experiencing tingling and numbness in her hands. These sensations continued on andoff through the work day. Claimant noted the tingling became more pronounced the harderthe work. Claimant acknowledged she experienced some symptoms of carpal tunnelsyndrome prior to working for employer, but such symptoms were relieved with aspirin andnever caused her to miss work or seek medical treatment. By November 16, however, thenumbness and pain in claimant's hands had become so severe she could not sleep. This timeclaimant was forced to seek medical care. Such testimony supports the conclusion thatclaimant proved an aggravation of a preexisting condition which was causally connected toher employment with employer. Cf. Williams v. Industrial Comm'n, 244 Ill. App. 3d 204,211, 614 N.E.2d 177, 181 (1993). This conclusion, in turn, is further supported by theopinions of both Dr. O'Conner and Dr. Raymond. Given such evidence, we cannot say thedecision of the Commission, as confirmed by the circuit court, is against the manifest weightof the evidence.

Employer also contends the benefits and expenses for claimant's conditionshould have been apportioned between claimant's various employers. First, employer raisedno such issue prior to oral argument on appeal. The matter is therefore waived. TransWorld Airlines v. Industrial Comm'n, 191 Ill. App. 3d 856, 866, 548 N.E.2d 367, 373(1989); Swanson v. Industrial Comm'n, 128 Ill. App. 3d 631, 634, 471 N.E.2d 200, 202(1984). More importantly, we have no authority to make such an award. The issue ofapportionment of benefits between various employers is a matter for the legislature toaddress first, not us.

For the aforementioned reasons, we affirm the judgment of the circuit courtof Cook County confirming the decision of the Commission.

AFFIRMED.

McCULLOUGH, P.J., and ZWICK, COLWELL, and HOLDRIDGE, JJ.,concur.