By seeing your history it appears that yoy are suffering from Malabsorption syndrome
which may be celiac/topical sprue, pernecious anaemia, glutein enteropathy
or irritable bowel syndrome
, so you need to be evaluated in detail to rule out the above causes just doing investigation for celiac sprue
may not able to diagnose actual condition, you may also require endoscopic biopsy at different sites, consult gasteroenterologist for further evaluation and suggest my advises also.