On 1/15/16 EE was helping install a return roller. EE crawled under the conveyor and turned to push up on the roller. When EE turned EE felt a sharp pain in EE's lower back. EE reported it to EE's supervisor. EE had no further complaints of pain until 1/29/16 which followed shoveling spillage on 1/28/16. EE was taken to the doctor and diagnosed with a lumbar sprain on 1/29/16.