What is wrong with me? low glucose, diarrhea, stomach pain , missing periods?

Okay about a year ago I had a colonoscopy because I was having diarrhea many times a week. I also was having stomach pains to the point it would be make sweat. This lasted for about 9 months. They found nothing.It got a little better but now the diarrhea is back and I can't figure out why. I also have a dull pain on my right side that I can not explain. I also am a nursing student and was practicing glucose tests in class. I took mine and it was 37 which is crazy low. I checked it again and the meter was correct. I ate something and felt better and my levels went back to normal. I told my doctor and he wasn't concerned. Now I have to make sure I eat regularly or I almost pass out. To let you, know I also have Hep B that is not active. I usually have normal periods but recently I have not been having mine, didn't know if that was a caused? I know this is a lot of information but a lot random symptoms have been happening and I'm just annoyed with it. Any ideas???