Are you on any meds? Could be erythema multiforme, which is a circular red rash with a white center, often causes by an allergic reaction or infection.
however, Some classic circular rashes are ringworm and Lyme, so it would be a good idea to have a doctor look at it.
Get tested for Lyme right away. If you have it, time is of the essence! It spreads fast. I had it for 10 months without a diagnosis and I've been treated now for 3 months with 43 symptoms! Trust me, you do not want Lyme!
YOU HAVE WHAT IS CALLED ECZEMA I HAVE THE SAME RASH AND IT DONT GO AWAY UMMM BUT WHAT U CAN DO TO KEEP IT CLEAR I MEAN IT WANT GO AWAY BUT USE UNCENTED LOTIONS AND SOAPS AND USE VASALINE TO KEEP IT MOSTRIZED THOUGH OUT THE DAY.