My dog has a weird mark on her back?

* Species: dog
* Age: 6 I believe
* Sex/Neuter status: female, spayed
* Breed: shih tzu Javanese mix
* Body weight: idk :(
* History: she has epilepsy and a lot of allergies
* Clinical signs: weird semi-circle mark on back
* Duration: just noticed it
* Your general location: Florida
* Links to any test results, X-rays, vet reports etc. that you have: n/a

for context, I was just cuddling my dog (her name is Bella) when I noticed a weird semicircle mark on her back that was inflamed. She does have a lot of allergies, and commonly scratches/bites at her skin, but she can’t reach her back. I’m kind of concerned it could be ringworm or something…