I strongly think in this case he needs to see a
Dr. and soon. You can start out
with a general internal medicine
Dr. who can lead him in the right direction. I agree his drinking must stop, but with all of his health issues, I think it's a bit more complicated than just rehab.
But has he seen a Dr. yet? I think you need to start there. And again, I think it's so great that you want to help him. The best of luck to you.