THIS ACCIDENT OCCURRED ON 4-15-03. WAS NOTIFIED ON 4-21-03 THAT THIS ACCIDENT OCCURRED. THE INDIVIDUAL BELIEVES IT HAPPENED WHILE BRUSHING/SCRUBING TESTING SCREENS VIGOROUSLY. SHE EXPERIENCED SEVERE CRAMPING WHILE PERFORMING THIS TASK. SHE DID SOMETHING TO HER MUSCLE OR NERVE IN HER LEFT UPPER BACK. SHE IS ON RESTRICTED DUTY.