I'm always so jealous of Frito Feet, lol, bc mine have never had it
! It seems like it'd be so cute somehow. I dunno.
Anyway, vet articles out there claim that Frito Feet is actually caused by yeast overgrowth, so your kiddo may have a localized or systemic yeast issue happening...are the ears smelly also, btw? To get rid of yeast, you need an anti-fungal. If you suspect it's systemic, then you may want an oral med from the vet like a round of Diflucan or Nystatin for a couple/few weeks. If you think it's localized, you may want an anti-fungal spray like:
Amazon : Amazon.com: Douxo AntiSeptic Chlorhexidine +...