So did you move him to the tub or not?? It's important to remember that boas are NOT ball pythons. They will generally not freak out in larger enclosures, handling them does not generally bother them too much, and they are generally garbage disposals when it comes to feeding. There are, of course, exceptions which is why I say "generally."
I agree with dragonboy. Your previous thread does not go into that much detail so its still hard to give advice when we don't know exactly what the situation is. Just how are you heating his current enclosure and how are you measuring your temps? It concerns me that you said he was always on the hot side. Your temps may actually be too cool. Pics would help a lot. In the meantime, here are a few additional tentative thoughts...
1) Use a temp gun to make sure you're heating up the prey item enough. The rodent should be at about 98-100 degrees. Know, don't guess. Or try feeding live a couple of times before going back to f/t.
2) Has he defecated for you? If so, what was it like? Was it normal or runny?
3) At this point, I would take him to a qualified herp vet just to be sure there's nothing physically wrong. Parasites could be an issue. If he checks out ok, you can relax and just let him settle in knowing he'll eat eventually. But have him looked over to be sure.