NO SPEIFIC INJURY- EE HAS BEEN EXPERIENCING INCREASING LOWER BACK PAIN OVER LAST SEVERAL MONTHS DUE TO BOUNCING IN SEAT WHEN OPERATING D9L CAT BULLDOZER. HE REPORTED OFF WORK FROM 8/26 TO 8/30 TRIED TO RETURN TO WORK ON 9/3 WORKED ALL DAY. BUT ON 9/10 LEFT WORK AFTER 3 HRS DUE TO BACK PAIN.