Hi Lisak
Is She still scratching and Bitting at it?
Is she Scratching and Itching all over her body?
Did you call your Vet and get some Revolution?
I would not put anymore of the YUK 2e on her. No Hydro-cortisone, I do Not think is safe to be Ingested. "She will like it off." You can give Children's Benadrill for allergies. See if that will help. If it is Mange Mites, Using The Revolution, You would see improvement in 24 to 48 hr.
It does not look round enough to be a RingWorm. Could she had scraped or pinched it in between something. While ripping out the Furr.
What kind of Cage is she in? Can you post what her diet consist of? What Formula did you feed her?
PS
You can take a cotton Ball with a little Alcohol, and Rub it over the spot.
See what that does. "It might sting a little so blow on it for a few seconds."