A necropsy might be a good idea. Cutting him open may well reveal the problem quite clearly. I know of several cases where people have pulled their hair out over reptiles for up to two years, thinking there was some form of infection or metabolic disorder, then when the animal was cut open and inspected, the cause has been clear. Things like foreign objects in the intestinal tract, a broken rib puncturing an organ causing problems with locomotion (this can be exacerbated when food presses against it, often causing regurgitation), there is a well known example of a death adder having a spinifex spine lodged in its trachea, that story was published in monitor. With a snake like this you'd be crazy not to cut it open and have a thorough look, for the sake of your piece of mind and the rest of your collection. There is a lot more you can do to a dead animal than a live one and a lot you can do a lot more easily. This would be worth doing even if you don't want to pay for it; ask around and get someone with a reasonable knowledge of anatomy and experience dissecting to do it for you. If it's something as obvious as a bone or foreign object causing a problem, even an undergrad biology student should be able to give you the cause of the problem. In third year I did a couple of dissections of dead animals to determine the causes of death, I'm sure if you ask your nearest university with a decent biology department they'll happily do it for free.
