I have a Rex/dwarf mix and the molts are terrible! Is the bald spot red? If it is just flesh toned, that is ok. The new hair just hasn’t caught up yet.
The best brush ever is the furminator. It is sold in many places, but is expensive everywhere. It is worth EVERY penny! http://www.furminator.com/deshedding-tools/small-animals/small-animal-deshedding-tool
My vet encourages gentle plucking. We have a lot of issues with GI Stasis, even though we up the greens and hay during molts and brush him A LOT. My vet this past time recommended we shave down his hair to super short next time he starts a molt– that way digested hair will be shorter. My Rex’s normal hair is short, but when he molts it becomes a decent length, with silver/white roots. I’m not sure if that is because he is a mix or not.
I haven’t tried this yet, but my vet also recommended using an ovenmit, with the sticky/grabby side, to pet buns to get loose fur off that the furminator doesn’t get.
My first buns wasn’t a Rex, but she got sick and needed butt baths. They sell dry rabbit shampoo that was amazing!