I totally understand the ups and downs. It took me a while after I was finally diagnosed to really accept what had happened. Even though the testing process took six months for me. It was like I couldn't stop thinking about it.
As to the doctor's training. I talked to a friend of mine who just got out of medical school, and she was like "yeah, celiac, a disease that kids get and leads to failure to thrive." That was the only context that she knew about it in. Not that it could develop in adulthood. Yikes.