I can’t tell you what happened. However, a lameness injury that hasn’t improved after 9 weeks has a poor chance for recovery. Lame bulls don’t make good breeders. The loss in muscle mass is from not using the leg. The lump may be the normal appearance of the hip (femur) on a non-weight bearing leg, or it may be evidence of an injury. Even though the lameness seems to originate from the hip, be sure that the foot is not the problem (for example a nail or sole abscess). There is a likelihood the bull is stifled, which is a ligament injury. Stall rest might help, although I assume he has had that. If he is valuable, consider taking him to a veterinary school clinic for evaluation.