Hi welcome to Health care magic forum.
Thanks for choosing H.C.M.Forum.
You have got stomach, back and shoulder pain
, more on eating certain foods.
You are also having diarrhea
after eating some foods .
The cause could be peptic ulcer
, gall bladder
pain, in tolarance to certain foods like casein
, glutin etc.
Other causes could be cervical spondilosis, or some other orthopedic causes.
Wishing for a quick and complete recovery.