I've Been Having Pain On My Right Side Like Under

I've been having pain on my right side like under my rib cage for a very long time and have had MRI's, CT Scan, and Hipa to rule out gallbladder, liver, pancreatic problems and nothing comes back. The back has gotten worse. I can't do sit ups since it hurts and I can lie on the side since it's tender and hurts to do that. What can it be?