Does wearing flip flops cause toenail fungus?

I have not had that experience, but I have had thick calluses on my toes. They collect dust until they feel like rocks. The skin swells between the straps. It is not obvious that these things are caused by wearing flip flops, but they clear up when you stop wearing them.

I suggest you put a TBSP of epsom salts in a pan of water and soak your foot or both feet for 20 to 30 minutes. Then brush your toenails with Listerine and a toothbrush.