foot odor is usually caused by an increase load of bacteria and fungus to the feet, which occurs from excessive sweating.
you can naturally treat the problem by:
applying starch to the shoes to absorb moisture. wear cotton socks and change them often. apply tea trea oil to the feet to ward off fungus and bacteria.
scrub the feet with soap and water in the shower. buy new shoes/ apply odor eaters liners in your shoes.