I Have A Pain In The Upper Right Hand Side

I have a pain in the upper right hand side of my abdomen that is sensitive to the touch. I especially feel it when sitting down. I have been in an elimination diet to see what foods I may be sensitive to and have been eating a lot of healthy foods. I have lost 5 lbs. in a week. I am thinking it old be my gallstones. I had a severe attack 2 months ago and got an spot. To see a gastroenterologist well after the pain had gone away. He ordered several tests: colonoscopy, endoscopy, and abdominal cat scan. Nothing showed gall bladder problems. I am wondering if those tests did not pick up a problem with my GB because I was not exhibiting symptoms.