Why does my toenail hurt after long runs?

Welcome to the latest episode of Ask Coach Parry. Today's question comes from Pacco. I'm not sure whether Pacco is a he or a she, but they are saying that they are experiencing pain on their middle toenail on their left foot after running.

What could be causing it?

Lindsey: There are a few things that could be causing the pain. If it is specifically on the toenail, there should be some blackening to, so if it is the toenail or toenail bed then there will be blackening of the toenail and that will let you know that one of the following things are happening: