I've been thinking about your post. You sound like a caring friend who wants to be there in the best way possible. You're saying you don't know how to help him: just wondering if you have ever asked your friend how you might best support him?

All you can do really is be there as best you can. All you can do is suggest resources or supports but he ultimately has to make the decision to accept them or not. If he doesn't want to see a psychiatrist, might he be open to counseling? You can encourage him to take care of himself by eating healthy, getting enough sleep, going out into the sunshine for a short walk around the block (or more).

Are you taking care of yourself throughout this process? You need to make sure you find things to fill your cup.