I walk a lot at work (8-12 miles daily), indoor and outdoor. Some days my feet are exposed to natures elements, cold, hot, wet, etc. Prior to this job my toenails were completely healthy.
However, now my big toenails on both feet are thinning and splitting. It's like the middle of the toenail can't keep up with the sides of the toenail. I trim the sides down to try to make it look normal, but it seems the middle is not growing, and is extremely thin. This has been going on for over a year now. What is this and how can I remedy it?