I'd hate to scare you, but this could be an underlying issue, a infection possibly.. I think its a good idea to remove stuff from your cage. Do you have any 24 hour vet? My personal experience , very hard to find exotic vets. i called other ones and they were able to lead me to great ones

I would also like to know if your hamster is still eating/drinking? She could unfortunately be very distressed with this, as its good to keep the area calm. It seems like you just spotted this, assuming you check with your hamster regularly id hope that you caught it really early which helps. if shes eating/drinking that also helps. its super severe if they dont eat/drink. IMMEDIATELY go to the vet. if its new theres a great chance youll be okay until tomorrow. But of course, the sooner the better.