Has anyone had these symptoms and the cause? upper back pain on the left side when swallowing, burping or?

about to burp. It is a steady ache for several seconds. Sometime I feel just a mild aching through their. I had an endoscopy which was negative. I do have gall stones, but never an attack and this is the upper left side of my spine? Doctors don't have a clue of what it could be. This has been going on for 3 months now and I am so tired of it. I have had labs and the only thing elevated is liopace. Please help!!