I suddenly lost my appetite. it's going on two weeks. if i eat my stomach hurts and i use the bathroom. what could cause this?

Anorexia: Appetite is a complex process mediated by the brain, emotions, metabolic needs, health of the gut & surrounding organs. Lack of weight loss would be good news here. I recommend a visit to your doctor to discuss the circumstances that preceded your anorexia & that may contribute to its persistence. Simple testing is appropriate.