Yeah but to people who are noobs to the green, everything else is a hard drug. Mushrooms would "fucked up shit". If he's slinging rock that's different. But I doubt it. Most people don't deal in both.
As for withdrawal, it doesn't really happen. Probably imagination. If you smoke all the time, like multiple times a day, and stop, it will take a few days sometimes a week, maybe a little more to clean out your system. You'll be feeling a little differently than you would if your system is clean, basically like when your smoking daily and haven't smoked all day.
No withdrawal.You make it sound as though weed is unhealthy? Other than the harm from inhaling any plant materials(which with green is minimal) It's actually quite healthy. Far better for you than the pharmies most people are prescribed.
If you don't want to smoke any more, or want to clean out your system so you can actually get really baked again, go for it. Just drink a lot of water.