From your description your pain seems to be neurogenic or psychogenic reason why any specific cause can not be detected on any imagery study.
Pain of neuralgic or psychogenic origin do not usually have identifiable causes as the nerves involved could be damaged or inflamed. Chronic inflammation of nerve or nerve bundles (chronic neuritis
), nerve compression by surrounding organs or extrasomatic objects, sequellae of previous affection like shingles, trauma, underlying systemic diseases such as diabetes, hypertension
, SLE, MS etc are possible causes of your chronic stomach pain. I do not know if your doctors must have done blood tests to rule out possible systemic or genetic diseases that could be the or
To treat this you will require analgesic
, antineuralgic and antidepressant medications
could be used to manage the pain. Antidepressants that have pain killer functions are of value here e.g amitryptilline.
Who to consult? You need to see an internist/neurologist
Hope this helps