Many things can cause fur loss with flakes and scabbing, like mites, fleas, fungal infections, and syphilis. I recommend searching for other rabbit vets to see if anyone has an appointment earlier for you: https://wabbitwiki.com/wiki/Choosing_a_rabbit_veterinarian#Rabbit_veterinarian_listings

I would make sure to express that the issue is spreading and he is now scabby — that is a sign that things are a higher level of intensity.

While there might be some temptation to self treat at home, it is dangerous to do so as there are flea/mite medications safe for dogs/cats that are actually toxic to rabbits (like Frontline; when treating the rabbit, best not use Frontline or other products with fipronil just in case) and also dosing for the rabbits and how often/when to apply should be done with veterinary guidance as well.

Yes, is it possible to call around to different vets? Mites usually aren’t an emergency, but if he has scabs and extensive fur loss then that would suggest the infestation has progressed significantly. However, I would not necessarily blame the cat. It’s possible your bunny has had this for a long time.

See if your vet has a same day sick option.

I can call this in any morning, drop them off and they will get to them when they can.

Good point, often if you call first thing in the morning they have some spots for urgent sick visits that they save (or cancellations).

Vets often do get cancellations, so this is a great idea!

did your vet have an answer to this? My bunny is experiencing something similar but we’ve ruled out all the normal options