Hi, Welcome to health care magic, Nausea just after eating could have many causes which are excess stomach acid secretion or acute gastritis,gastric ulcer or Helicobacter pylori infection or food allergy. He must undergo routine blood investigations and H.pylori,liver function tests,urinalysis and stool for blood,abdominal ultrasound and upper gastrointestinal endoscopy to detect the underlying cause. Treatment is mainly depend on the cause but you may take symptommatic treatment meanwhile. Antacids like h2 blockers (ranitidine) or proton pump inhibitors (pantoprazole or rabeprazole) will help to reduce excess acid production in stomach and antiemetic (ondasetron or metoclopramide) to relieve from nausea or vomiting. He 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, eat plain foods like boiled rice and green leafy vegetables without adding spices or oil. It will help to neutriluze digestive acids and also they are easily digestible means there will be no need of extra stomach acid and no acid reflux. Consult gastroenterologist for further advise. Thanks and regards,