OK good it really looks like ring worm but again there are others more versed in all things Yorkie
I do know the symptoms of Lyme disease and she doesn't sound like she has them. Our Boxer had Lyme disease and she was very lethargic and her appetite changed completely. Here is a link with info.
Lyme Disease Symptoms in Dogs
As a side note I would take her to the vet to make sure and if its ring worm get a topical treatment.