Toenail falling off....WTF??

One of my toe nails is randomly falling hasn't completely yet but it's going to and it's really weird because I didn't do anything to it that I'm aware of..haven't bumped or stubbed it or anything! Should I be concerned..? Or just let it fall off and leave it be? Never had this happen before so I'm just seeing if anyone else has? It doesn't really hurt but it's really uncomfortable especially when walking/wearing shoes..and I don't know if it looks weird or nasty because I have pink nail polish on my toes and am nervous to take it off. Any ideas?