It definitely looks like fungus to me. She needs to see a vet now, I have seen a chin eat through their skin when they had fungus, and she looks close, so she really needs a vet. Antifungal meds will most likely be prescribed, and I would use blu kote (found in feed stores or online) to sooth the skin a bit and it does help with the itching. You need to be very careful and sanitize the cage every day or she will keep getting it back.
