What you are doing is really good. I'm sure you are concerned and you want to help him but sometimes if people don't want to open up you can't force them. I would advise you to talk to him once and let him know that you are there for him and that you want to help him and see what he does. You can't force him to open up, just show him that when he's ready you are there. Support him and show interest but don't force him!
Good Luck!