I've had a stomach ache for about a week and it comes in waves and it's like getting punched in the stomach and it subsides for a bit then eventually comes back, and I've been popping only dark green to brown liquids and it's been just water coming out with very very few little pieces of solids, this has only happened twice in the past week, once on first day and a week later again, what is causing this? A little background is I'm in a foreign country Vietnam to be exact I don't know if this helps at all or not, my diet on the past two weeks has went to prinarily fish foods.