With those circumstances, I would hesitate to jump to an IBD diagnosis. My (admittedly limited) understanding of IBD is that it won't lie dormant in a ball python for that long. Generally you will see physical symptoms manifest within a few weeks and it kills pythons quickly. My first thought was neurological damage from overheating, but if nothing has changed about his setup, I don't see how that could be. How are you regulating the lamps and UTH or are you? I guess if you had them on a thermostat/rheostat and the stat failed, it could be running your heat sources at 100%, which could get too hot and overheat him. Was this a sudden onset thing or did his condition deteriorate over time? Either way, I'd probably be trying to get him to a vet ASAP. I hope he pulls through for you.