I have pain in the lower left side of my back and appears aaffects my knee . THe pain sometimes is worse at night time. Also when I eat spice food gas pressures down in my left side of the stomach and I feel that pushes down to my pelvis , which make me got to the restroom to unrinate. I am 60 years old. My dotor has conducted several test, scan in my liver, bladder and pancreas with good results.
In my opinion, you have two probs. One non ulcer dyspepsia and lumbago. You are advised to get upper g I tract endoscopy and MRI scan of l s spine. Please don't take any analgesic except tab tramadol everyday night after dinner meanwhile.