Stinky Feet + Tiny Room = Unhappy Roomate...Solutions?

Hopefully, he showers daily. Next, he should be wearing only cotton socks and changing them daily. Next, he needs to put his shoes/slippers outside in the sunlight which will dry out the linings of the shoes. This smell is coming from sweat so all his measures should be at eliminating the sweat from his shoes and socks by changing a few things as I have suggested.