EE was pushing rock screens with a 375 Komatsu dozer when he began to experience problems with the dozer. Mobile mech.came to diagnose the problem. EE raised the blade put the dozer in drive,the dozer moved forward 5' and then jerked hard twice.The EE continued to push screens up the pile when his neck stiffened up. EE was seen by the doctor and given RX meds.and work restrictions.