If they are not painful and they are circular with hair missing, is may be ringworm lesions. I would make sure to wash your hands and try not not touch it anymore until you get your vet to confirm this just in case. Ringworm tends not to be painful but it is contagious so washing after handling her is your safest bet. Your vet will be able to prescribe medication that will get rid of it.
Good Luck!
Disclaimer: The above is provided for informational purposes only. As I am not a veterinarian -- the above should not be considered, or relied upon as, veterinary medical advice. I strongly encourage you to consult your own personal Licensed Veterinarian regarding any serious animal medical matter as they will be able to see and exam your pet.
Let me know if you have any other questions
Good Luck &
Best Fishes