Hello doctor, my boyfriend has a bad upset stomach, he always go to the bathroom to poop and he has watery stool, he can feel burning sensation in his stomach like he said its like an acid or something. Everytime he wants to eat, he always go to the bathroom. After he poop, he feel the burning sensation in his stomach. What is that doctor? I m a pharmacist student so he asked me about meds, i suggest metronidazole because i suspect its amoebiasis.