<s>[INST] I have lower stomach pain, now accompanied by lower back pain. I've had symptoms for a couple of months, but usually just after I eat-and I feel super full of gas. Now it seems to be more frequent-and the pain is worse. I've had a CT and they said they didn't see anything...but this pain is BAD. [/INST] Hi. CT scan has no power to see and diagnose everything , although this is the best investigation for abdominal pain. You have a classical complaint lower stomach and back pain after food with acidity. This can be caused by colitis( inflammation of large bowel) the pain increases as a reflex from a full stomach. I would advise a  stool test, colonoscopy may be enteroclysis. </s>