EMPLOYEE FELT TWINGE IN BACK ON 3-21-01 WHILE WALKING FROM WORK AREA. THE NEXT MORNING, HE WAS STANDING IN LUNCHROOM WHEN HE COUGHED AND HIS BACK SPASMED. EE WENT TO DR WHO GAVE HIM SOME MUSCL E MEDICATION AND ADVISED HIM HE COULD RETURN TO WORK WHEN HE FELT BETTER. HE WENT BACK TO WORK ON THE NEXT SCHEDULED SHIFT.