I read once that a good idea is to keep a little pump container of soft scrub with bleach in the shower, and scrub the footsies (especially around the toes) with it a couple times a week with a toothbrush or something.
It's supposed to exfoliate and protect at least against bacteria and fungi. I don't know about treating it though. It's something I've been meaning to do for a while now. I don't have any fungi problem, but I get wicked calluses all the friggin time. Even the ped egg is no match for my amazing big toe callus.
Anyway, hope this helps! And congrats on the MBA!