That happened to a buddy of mine but not after drinking, he had a sist on his tail bone or something like that. He said he didn't feel good and said his ears started to ring wich got my attention. Then he stood up and the chair he was in was full of blood. My first thoguht was OMG he is gay. But the sist(sp?) popped and a shit ton of blood ran out of his ass. Go to a doctor.