good socks of course and regular washing. do air it out and if possible, do so in the sun.

I agree with MoM93821 – alternating between shoes is really important, as is changing socks every day. Also, your son could apply some tea tree oil to his feet daily. This will kill off any bacteria causing the smell, and tea tree smells better than stinky feet.

Visit your chemist,they have powder for sweating that you could apply to his feet!

A podiatrist visit might be a good idea? They really can help with stinky feet. Also, all shoes when worn need to be aired for 24 hours after wearing otherwise they stay wet and moist. Maybe invest in a few pairs? Good cotton socks are necessary too when wearing shoes. Plenty of time for feet to breathe when at home – so plenty of bare feet and air. You may have tried all of these things already? Good Luck!