Not sure if this is a tad late or not... But I'd be concerned for consistent right sided stomach tenderness or rebound. If it started recently, you could potentially have appendicitis or a burst appendix. You could also have some bowel issues affecting the right side or some sort of gallbladder issues like cholecystitis (however pain can be felt in the right shoulder at the same time).
In other words, I recommend going to the emergency room... Appendicitis is a very serious and potentially dangerous concern.
