I am not a doctor...but my son had ring worm last year. It could be ring worm... you can keep it covered, because it is highly contagious. We went to the doctor and got some cream to rub on it... but what took it away was regular bleach. Apply it in good amounts then cover it back up... You can also use Athlet's Foot products too...Don't let him use the same towel... it can spread to other parts of the body... wash all of his clothing in hot water too.