CJ
I don't know where you live, but I would pack him up with his medical records, etc and take him to the Mayo Clinic, the Cleveland Clinic or Johns Hopkins Hospital, etc for an evaluation. They have wonderful doctors who deal with very difficult cases. Since they are teaching centers as well, they are up to date on everything. Ask your doctor to refer him for a second opinion to an Internal Medicine Doctor there or another specialist. Good luck. Don't give up on him just because they can't find a diagnosis!!