Hiya there. From your description it does appear to be one of the 'gyrate' erythematous skin conditions. More often than not, it could be a 'reaction pattern' following some sort of insect bite reaction as if it were fungal origins, there would have been some discomfort. Might i suggest using a topical combination cream of a hydrocortisone
& antifungal applied twice daily for a 3-5 day period. It should clear up completely. If not, then you need to fix an appointment with your nearest dermatologist
& have it biopsied if only for academic interest. I envisage no problems & nothing serious to write home about. Good Luck & Godspeed!