I am unable to eat. Everything I eat makes me feel nauseous. But if I don't eat I'm hungry as hell.…

I am unable to eat. Everything I eat makes me feel nauseous. But if I don't eat I'm hungry as hell. It really sucks. I have no idea what to eat. & for some reason I'm feeling pretty down. My moods have been all over the place. One second I'm really happy, the next I'm really sad, & then really angry. The littlest things have been setting me off.