While an ultrasound of your abdomen sounds like a good idea (which is the test they use to check for gallstones), you might also ask about an upper endoscopy. A scope is inserted down through your esophagus, into your stomach, and into to the first portion of your small intestine. They can check for ulcerations, inflammation, erosions, etc. If you have adequate health insurance you may ask about getting such a test to check on the health of your upper intestinal tract.
Let me know if you have any other questions and I hope everything goes well at the doc's!