Hi, thanks for posting your concern in the HCM. I think back pain after gastric bypass needs further investigation particularly when you have an elevated ESR. Depending upon the location, back pain can be considered due to numerous reasons. If the pain is in lower back, spinal abnormalities, mechanical back pain due to faulty posture, urogenital infection including PID, colonic pathology should be ruled out. As your doctors have already performed imaging I think any obvious spinal abnormality has been ruled out. If you have not yet done a routine urine examination, you should have it done at the earliest. Your should also have a stool test done for routine examination and OBT. These are important because you have a high ESR which suggests some infection or inflammation. Mechanical back pain may not display any obvious abnormalities in these test. It is due to faulty posture or prolonged sitting etc. It may be relieved by correction of posture and abdominal muscle strengthening exercise. I will particularly emphasize this because you have a history of abdominal surgery in past which might have caused lax abdominal muscles resulting in overload on paraspinal muscles. In case of pain in mid or upper back, a serum amylase and lipase test and liver function test should be done to ruled out any liver or pancreas problem. Last but not the least, anxiety disorder and functional problems like regional pain syndrome may pose with similar problem. You should also start daily relaxation session for at least 30 min just before going to bed. For any further information please write back. Regards, Dr. Kaushik