Yes it could be a ringworm witch spreads all over your body if you don't do anything about it, its shaped like a ring, and the worm is in it traveling through your skin. Try freezing it by putting ice on it, or getting some Tetterine ointment from your pharmacy, or see your doctor.
You can treat ring worm with the same medication that you use for Athlete's Foot. Just get on it fast before it spreads. It does take a while to get rid of. Just keep at it and it will clear up.