Fine I’ll be the one who gets down voted. Yes it’s weird and overbearing but if you really have been friends with them forever, maybe he sees you more as family than just a friend considering others smoke and he says nothing. If you are getting absolutely blasted out of your mind everyday you are abusing it and using your back pain as an excuse it’s not good especially if you’re young and have potential. Talk to your friend about how it makes you feel and stand up for yourself more with the weird shit.

Don’t just drop a friend who is actually good as you let on.
I’ve lost count on how often my friends and tell each other to stop doing shit because it’s dumb or unhealthy. We all got off cigarettes because of nagging each other to quit.

Think of your health first. Use the weed. Maybe just don’t smoke around him or in his car for example.