Is It Common That Bruising Toenails Can Impede Walking?

I like to treadmill walk for exercize. The last few weeks the toenail next to the big toe, gets bruised and looks like its going to come off. This is on both feet! could it be a shift in how I am walking, I have had some low back pain and wondered it that could contribute. Is this common that bruising toenails can impede walking? They actually hurt quite bad 3-6 hours after a workout.