Hey Eric,
I had UC, and have a 20 year old pouch. Diagnosed (approx. 4 years ago) with fibro, chronic fatigue, chronic pain, anxiety/depression etc. I am not sure what the connection is, but it seems to me that the large intestine is involved in more biological functions than just waste storage and removal. I have posted links in the past on how the intestines function as our "second brain". God only knows the answer to your question.
Markus