BLOW TO LOWER BACK PAIN WHEN MOVING?

i have recently took a hit to my lower left hand side of my back (scaffolding tube dropped on it ) i then stood up as i was bending over to walk it off took two steps and then dropped to the floor ever since i can barely walk as some movements really hurt and want to make my leg give way underneath me with the pain could it be serious or just a bruised tendon any light would be gratefull PS ANY EXCERSISE I CAN TAKE OR PAIN KILLER TO HELP WITH PAIN ?