Kay (Fl, US) on 05/31/2014
Dear Desperate NY: What you describe is "classic" ringworm of the scalp (it is a fungus); there are great photos of this ailment on Web MD. My brother's family picked up a spot on arm & leg; the best/fastest treatment (after trying many) came from the dollar store (in the USA) called "Blue Goo"; found in the foot section, for nail fungus; cost $1.00 for an 4oz bottle (which was enough to treat ringworms, toe fungus, and yellow ingrown toenails too)! It's 1% clotrimazole cream plus tea tree oil. They applied it before bed, let it dry, then climbed into bed, washed it off each morning, after about two weeks; cured!
I tried the remainder on the (lifelong) calluses and ill-formed nails one my funnky little toes; the calluses flaked off and the nails grew out normal!