Your description suggests ringworm, a very common and highly treatable fungal skin infection. Please don't worry, as it usually clears up easily. You can treat this with over-the-counter antifungal creams. Look for generic options containing clotrimazole, miconazole, or terbinafine. Apply a thin layer to the rash and about an inch of the surrounding skin twice daily. Keep the area clean and dry, and wash your hands after application. Continue the treatment for one to two weeks after the rash disappears to ensure it is completely gone. If it doesn't improve after two weeks, please consult a doctor.