Good luck with the feet! I've never gotten into it myself, but I know a lot of people who swear by colloidal silver. It makes sense that the silver ion is required to be active--elemental silver is quite unreactive. There's a reason it's called one of the "noble metals".

If you haven't heard of the podcast, I recommend checking out Beyond Wellness Radio. It's two doctors chatting about a specific health subject every podcast, and they are constantly going over the importance of diet and hormones. I would wonder if your athlete's foot has something to do with those two things.