Hi. Thanks for your query. Noted the history and understood your concerns. There are many reasons for not gaining weight hence should be sought after by a Clinical evaluation by your Doctor, get relevant other investigations like tests of blood for thyroid, liver, pancreas, ultrasonography of abdomen, X-ray of the chest and so on to get to know the cause and thus possible to get a management. Gas, belching, pain and soreness under left rib and back as if someone punched you can be detected by an Upper GI Endoscopy, colonoscopy and contrast enhanced CT scan of abdomen. Once a proper diagnosis has been made the management becomes specific and effective.