If you've only been with him for a month you need to decide soon if you want to break if off or not. I'm certainly not giving you advice to break up with him, but the longer it lasts the more it will hurt him when it ends.

The being said, like the other comments said you really need to be patient. It's really kind of you to want to help, but it's something that unfortunately cannot be helped sometimes. No amount of comforting or affection can overcome what might be going on in his head. The best thing you can do is just be there for him. Don't try to offer advice or any kind of solution, just be there. Hug him, tell him that you care, tell him he's not alone, etc. Most people don't want sympathy, but compassion can make a big difference. Again like the other comment says, don't stop speaking to him unless he specifically asks you to. He probably seems really distant right now, but hopefully after some time he'll go back to the person that you knew before. People hit really low points at unfortunate times. You just kind of have to believe that he'll get through this and be there for him along the way.

I've been on his side of this and I know it's really easy to push someone you care about away. If you do care about him, don't let him do that to you for both his sake and yours.