It could be ringworm or many other things, she really needs to see a vet to be properly diagnosed and treated.
Why Does My Dog Have A Circular Bald Spot With Reddening On Her Face?
In addition, you don't mention breed (considered par for the course in some breed's almost) or age but demodex quite often show's up like that initially. If that's the case talk to your vet about ivomec (can't be given to some breed's) or interceptor (safer) as a treatment as they are usually effective faster and less complicated than dips. :-)