I'm 16 and ever since my last period about a week ago I've had a lot of problems. I've been dizzy when standing, had random stomach pains, I don't even want to eat and get sick when I do, I've had blood in my stool (I've had this problem before, and doctors have no idea what it is), I'm always thirsty, I have no energy at all, and I have daily headaches that turn into migranes after a few hours. I don't know what's wrong, and it's really starting to worry me. Does anyone know what this might be? Please help!