Sometimes young animals scratch themselves a lot. It’s one of those things like hiccups, you see it a lot on young animals, not in adults.
Anyway, you can treat the carpet with diatomaceous earth for 48 hours, then vacuum it up. It can be a lot of work to get it out but it killers mites and other bugs by desiccating them, and it’s non-toxic. The bun should not be let on the carpet while the earth is on it, just to be safe. It’s a fine mineral powder and not good for the tiny bun lungs to breathe in. As for treatment, you do a repeat treatment after a couple of weeks so any mites that hadnt hatched at the first round of treatment will be killed. I had to treat my bun Bam for mites, we did two rounds and they never came back. I just did normal cleaning of his area, but the room wasn’t carpeted. I washed everything that could be washed. Toys and stuffies can be put in plastic bags in the freezer for 48 hours.
You want a vet that’s used to handling bunnies. Bunnies are notorious for being skittish at the vets, and all reasonably rabbit savvy vets know this. Bring a fleece blabkie or a towel to wrap him in or to put on the table, vets tables tend to be slippery for bacteriostatic reasons. A carrier with a top that can be removed can be good, because that way the bun can remain in the carrier when the vet listens to the heart etc.
You’re very welcome to ask any other questions that might crop up 