You poor thing - it's so difficult not to know what's wrong with you, especially after going through it all once already with coeliac.
Right now, I'm going through something pretty similar with my husband. He has various health problems but the diagnoses and treatments haven't been enough to make him better. We have an appointment with an endocrinologist in March and I'm almost hoping for a diagnosis of Addison's just to know what's wrong. The point I want to make is that, from my reading, Addison's seems to be a little like coeliac in that it can do terrible things if left untreated BUT can be managed pretty well if it's diagnosed. JFK had it, in fact, and he coped pretty well. So - please try not to worry.
Hoping for the best for you. Keep on at those doctors until they figure things out!