I Have A Pain Left Middle Back Just Below The

I have a pain left middle back just below the end of my should blade. Pain feels more inside my rib cage. I have a peripelvic cyst or a few in my left kidney. CT without contrast for lower back pain done last April along with an abdominal ultrasound. Middle back pain came in September and comes and goes. Sometimes disappears for 10 or more days only to reappear for a few days then goes away. When present, pain seems worse at night. Got X-ray and another ultrasound in December to check pancreas and spleen, which looked normal. X-ray revealed t6 and t7 vertebrae slightly shifted. Had endoscopy in December for mild upper left abdominal pain which showed mild to moderate gastritis. Meds for gastritis helped stop abdominal pain but not back pain. Never smoked and nothing picked up on X-ray re the lungs. any thoughts?