They sell something at Lowes for odors--pet odors and all sorts of odors. I heard the name before but right now I can't recall it. Ask them at Lowes for a spray that neutralizes odors. They will know what you're talking about.
There are a few things you can do. As others have suggested, make sure your feet are clean and wear (clean) socks. Give your shoes a break and don't wear the same ones every day. Also, you can use deodorizing foot powder after washing & drying your feet. At the end of the day, sprinkle some baking soda inside your shoes, then lightly stuff some crumpled newspaper inside them. Both the soda and newspaper will absorb odor and moisture. Let them sit like that until you go to wear them; remove the paper and shake out the soda. It's fine if there's a little soda in the shoes after shaking out most of it; it's not going to hurt your feet.