You must be going through withdrawals now but I hope things get better soon. I highly sympathize you because I lost a friend to the same problem. I hope you can get your friend back and end this pain on you and him.
I was the same way (having no idea what to do) and I had to let my friend find out their solution on their own. I pray the best for him and be by his side for as long as you can (a chance I never got).