I tried everything from ignoring him and screaming "ouch" when he bites. When I isolate him in a room or in his crate he barks really aggressively and bangs against the door and walls until I come back. Twice he has even peed in the room and then lied down at the door waiting for me to come back. When I leave him outside he doesn't care and just falls asleep and when we start to play again he bites me again. How do I stop this behavior he doesn't seem to get the message he is 15 weeks old.