Employee was loosening case mount bolts from the frame to the case on 3C tails pump working in a bent over position he felt a strain in lower back. He was using a 3/4 inch ratchet with a 2 1/4 inch socket to loosen the bolts. Did not seek medical treatment (physicial therapy prescribed) until 11/16/09. Did not notify United Taconite of medical treatment until 11/17/09.