I am not a doctor and have no idea if this is what you're going through, but two of the families that we know from our JDRF circles are dealing with Type 1 and celiac disease. If you Google that, there are pretty suggestive news articles that link the diseases together and our dietician has given us an informational pamphlet on celiac.
The only reason I mention it is that one of the families had a 14 year old girl who was going through exactly that (plus a couple other symptoms) and switched to a gluten-free diet. She started feeling better in less than two days.
Again, I don't know much about the disease and I'm in no position to diagnose! On the other hand, going gluten free for two days isn't that hard, so it might be worth a shot?
Whatever it may be, I hope you're feeling better soon!