Hello ticktock
I know what you're talking about because you're describing very much how I was. The good things in your situation is that he's admitting it and is talking to you and that he's young enough to do something about it and still have most of his life to look forward to. I left it a lot later. Of course seeking help is his choice but you can encourage him - it sounds like that particular door is slightly open already...
Best of luck.