EMPLOYEE STATES THAT HE FELT DISCOMFORT WHILE REPAIRING THE DISC BRAKES ON A 1985 HAUL TRUCK. HANDLING CALIPERS AND MANUEVERING A TIRE CAUSED MUSCLE STRAIN. WHEN EMPLOYEE REFERRED HIMSELF FOR MEDICAL TREATMENT, ON 5/22/03, HE WAS GIVEN PRESCRIPTIONS FOR PAIN AND TO RELAX HIS MUSCLES.