Why is he doing all this?!?

well you should tell him that you don't like to see him doing that to himself and see whaqt he says

You can try confronting him. Speak to him in a loud, assertive manner about all your worries. Unfortunately, something like this will likely have to run its course. He's lashing out and self-medicating for some reason, I'm not sure why, but more often than not there's nothing we can do. Breaking through someone's self-defense mechanism takes months of training and effort and knowledge and a natural affinity towards it, so really, for most people helping others like him won't help.

You can also try being calm and caring to him if being assertive doesn't work, though assertive behavior usually helps breach someone's self-defense mechanisms.