So, the cause is there are more than 250,000 sweat glands in each human foot, along with a host of bacteria that live on the skin's surface. Bacteria break down sweat molecules, with the side effect of creating an acid with that foul smell. The solution is to apply an antifungal foot spray or medicated foot powder(which you'll find in pharmacies) on your feet once daily. Sometimes in setting medicated deodorant insoles into your shoes helps. If you need to quickly cut down on your foot odor, it's safe to apply deodorant spray to your feet. Hope it helps.