WHILE LIFTING THE PUMP/FILTER UNIT FROM ONE PORTABLE FUEL TANK TO ANOTHER THE EMPLOYEE FELT HE PULLED SOMETHING IN HIS BACK. THE EMPLOYEE CONTINUED TO HIS WORK DRIVING A TRUCK AROUND 0830 THAT DAY THE EMPLOYEE REPORTED THAT HIS LEG WAS GETTING NUMB AND HE WAS TRANSPORTED TO THE LOCAL CLINIC/HOSPITAL COR CARE.