EE WAS STACKING BAGS ON A FLAT-BED TRUCK, HE WAS GOING TO THROW A BAG ONTO PALLET WHEN HE FELT A SUDDEN PAIN IN LOWER LEFT BACK. HE SAID HE HAD SOME TROUBLE BREATHING. HE TOOK ONE DAY OFF TO R ECOVER. THIS ACCIDENT REPORT WAS RECEIVED BY SAFETY OFFICE ON 10-8-03.