[Amethyst_ice]

Hello

Fur loss can be down to a number of things

Mites tends to be the first port of call to treat for. You could ask the vet to do a skin scraping which would confirm mites and he may need an injectable form of ivermectin

Is it possible to get an appointment sooner? I'd be inclined to phone the vet and sey it is much worse and he is in distress. It can make them poorly and more likely to be infected if it is red and raw.

Cushings is also a disease, more common in older hamsters, which characteristically has fur loss. However, as you say it looks red and raw i'm more inclined to believe it is a skin condition.

I hope he can get some relief soon. You may ask the vet for some metacam (pain relief) for him also

Keep us updated and good luck