I had ringworm for many years, and tried many treatments. Finally, "Vetericyn VF Wound & Infection Treatment," which is made for pets, got rid of it. I simply sprayed it on the ringworm several times a day. It's actually a form of bleach, but it's safe to use on the skin. I first learned about it when my vet prescribed it for my dog who had a bad fungal infection in her ears and eyes. It's great for all kinds of wounds.
They also make a gel form, which stays on much longer, but it's only half the strength.