M.S.
As the others have said, you need to go to leather. After 3 bouts of athletes foot before my oldest was 2 1/2, we gave in and only buy Stride Rite - they seem to be the only brand that is ALL leather, not a combination. Yes, they can be pricey but it just means my kids have three pairs of shoes only - one sneakers, one for church, and one pair of sandals (leather only) in the summer. Its all they really need anyway. Sounds like your little guy has the same issue of feet needing to "breathe." The only place he NEEDS shoes is outside to prevent cuts, etc - let him go barefoot wherever possible - its actually better for his feet. I'd avoid the crocs - my doc said she's seeing a large number of kids w/fungus problems from wearing crocs without socks.