do you have abdominal pain?
diarrhea?
blood in your stool?
weight loss?
I know those are kind of embarrassing questions, but they're important. It's possible you have a bowel disorder. I've had Crohn's Disease since I was 11 (I'm 20 now) and it's not a fun thing to deal with. It makes having an active social life a bit difficult if you don't take care of yourself properly. You really should see a specialist. Getting proper medical attention sooner is a lot better than waiting for it to get worse.
Before I was diagnosed I was in really bad shape. I had crippling abdominal pain. I always just passed it off as bad gas. I was about 4'9" and I only weighed 60lbs. My ribs were actually hurting me. After I went to a specialist and received antibiotics, I could finally live life normally (somewhat) again.
I'm not saying this is what is wrong with you, it's more likely you have some bacteria in your bowels.
If you don't see a specialist I will be forced to tell you some of my own horror stories.