Well, without a clinical evaluation it would be difficult to determine the cause of the pain. Mid-back could be related to gastritis/ peptic ulcer, pancreatitis, spinal issues, neuro-muscular causes, cardiovascular abnormalities etc. If you have history of gastritis, you could try taking OTC antacids and see if these seem to help. If these bring little relief I would suggest consulting a primary care physician or an internist for a primary evaluation. After a cause is identified it can be managed accordingly or specialist care may be sought.
Hope this is helpful.
Thanks so much for your reply, very kind of you. I had ultrasound on kidneys/pancreas/spleen/liver and gall bladder (all ok) and a spine x-ray that showed DISH. During all this the back pain was abating and I had gotten some back massage from Core Fitness. Then an arthroscopy last week on my right knee last week (which was successful). Since then there has been very little back pain, just a bit of tightness but none of the constant dull pain. Perhaps my knee had thrown my back out. The knee joint was uncomfortable but nothing like the pack pain and I didn't relate the two.
thanks again for your input, Dr Kaul.