What's wrong me? Endoscopy/colonoscopy normal. Would a capsule endoscopy help find something?

You are only 15, gosh. Some of the symptoms are what I had prior to finding a cancerous tumor in my colon. I don't see how all your tests have come back normal with all the symptoms you are describing. If you are bleeding, for example, you might have ulcers or cancer somewhere along your digestive system, and with the bleeding you are probably anemic which would have shown up on your tests. The anemia will make you tired and dizzy. Your blood counts were normal? Iron was normal? Biopsies were taken from your stomach and colon and they were normal? If all your tests are normal then you might be eating something that is causing your problems.