Tinactin will work as will Tea Tree Oil and Oil of Oregano. I've also read a number of posts recommending gentian violet. I haven't tried it, but it's also recommended by Merck to treat resistant fungus and yeast (ringworm is a fungus):
You might also want to search "ringworm" in the Curezone search box since Curezone has a support forum for ringworm with excellent information. It's not as active as other forums, though, so you have to conduct a specific search to find the information in it.