Trying to determine what the source of the issue was.

read more 
My serious guess as to what's going on: 

I have GERD with depression/anxiety and maybe normal sinus issues.

The only thing I really want to fix is my abdominal pain. That's what really gets me down. 

I really think that stress about falling behind with work has been big. Working usually is what makes me feel better. Maybe there is some minor stomach stuff, but I kind of use it as an excuse to neglect work, and then I focus on it and it just feels worse and worse. In fact, it's not that bad and working is really what I need to do.

Another thing that seems huge: keeping a positive attitude toward it. Tara's totally right: don't just sulk and think about it all the time, move past that. Try to be happy.