Aquatundra, I was having those same symptoms, which unfortunately could be caused by a lot of things. In my case, I just got diagnosed as having an H. Pylori infection. I was getting treated for IBS but it really wasn't helping so my new doctor thought it might be this bacterial infection. Turns out it was! It doesn't hurt to ask to get tested for it, right? At least it's something you can rule out if that's not your problem. I wish you the best of luck. I know how awful it is to deal with stomach and fatigue. Hang in there and keep looking for answers.
Delfin