Hi slate01...Normally you would use Methylene Blue orally as described in my original post. Methylene blue will also stain you skin blue.
For all topical problems on the skin, I use an equal mix of 3% hydrogen peroxide + milk of magnesia(or Epsom Salts) and then just saturate this solution with borax crystals (20 Mule Team Borax ifine) until they no longer dissolve. I make small amounts -- a capful at a time to use and just dab it onto the skin using a cotton bud. This mix will kill all fungi, yeast, bacteria, parasites and viruses topically and is quite safe to use.
I just buy the Methylene Blue from Aquarium shops, this is good enough quality. After all, fish are very sensitive to heavy metals and toxic substances in their water(more sensitive than us), so this form of methylene blue has to be fairly pure otherwise nobody would use it for their fish.