Thanks for providing more information.
Well ringworm is a possible cause in your case.
Ringworm is a common cause of a flat red area, and we would expect the area in the center to become more pink as the ring spreads.
I would suggest ten days of clotrimazole or miconazole 1% cream twice daily to see if it helps.
Ringworm can be contagious so wash your hands,avoid sharing clothes,bedsheets,towels,etc.
Other possible causes may include Granuloma Annulare and Erythema Annulare Centrifugum that are two conditions that look like ringworm.
If you have history of tick bite then this circle can be associated with it and you shouldn't ignore it and consult a doctor ASAP.
And if your symptoms 'll get worse over the time then consult a dermatologist for skin scraping for further evaluation and management.
I hope this helps.
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