Hi, Welcome to health care magic, Burping or belching is the way of body to expel stomach gas out of it. Stomach upset or nausea, fullness in stomach could be due to acute gastritis, gastroenteritis or Helicobacter pylori infection. You should undergo routine blood investigations and H.pylori,liver function tests,urinalysis and stool for blood. abdominal ultrasound and endoscopy you had already done before. Treatment is mainly depend on the cause but you may take symptomatic treatment meanwhile. Antacids like h2 blockers (ranitidine) or proton pump inhibitors (pantoprazole or rabeprazole) will help to reduce excess acid production in stomach. You can also take digene gel or liquid or ulcero-protective agents like sucralfate or bismuth subsallicylate to reduce the burning sensation. Apart from medications you should also try some non-medical or dietary measures, 1) eat plain foods like boiled rice and green leafy vegetables without adding spices or oil. 2) avoid oily,spicy and fast foods 3) avoid eating full stomach at a time rather have small meals frequently. You must see gastro physician who can examine you properly and prescribe the treatment. Regards,