EE REPORTED TO HIS SUPERVISOR THAT HIS LEFT SHOULDER WAS SORE WHEN ASKED TO MANUALLY FILL 50 LB. BAGS OF CRUSHED LIMESTONE. HE DOESN'T KNOW WHEN HOW OR WHERE HE INJURED HIMSELF. HE MAINTAINED THAT HE WAS NOT INJURED AT HOME. HE WENT TO HIS OWN MD WHO SAID INJURY WAS WORK RELATED. SENT EE TO COMPANY MD ON 3/25. MD IS TREATING INJURY AS WORK-RELATED AT THIS TIME. UNDER INVESTIGATION.