Toenail turned purplish blue color

My entire toenail on my second toe on just one foot is turning a purplish blue color. It started about a week ago where my toe nail sorta hurt.... not bad... just sorta tender. Now about 7 days later it is completely purplish blue in color. The entire nail, it doesn't hurt anymore though. I can wear any type of shoe and it is fine. I've been told that runners get this a lot on their big toe... and I do work out 5-6 days a week for about an hour and a half-2 hours a day... running only about 30-40 minutes and on the eliptical or cross trainer the rest of the time. I was a very competitive sprinter in high school and also played basketball (point being.... lots of running) and this has never happened before. Has anyone heard of this... or got any other suggestions? I don't want to go to the doctor for a stupid discolored toenail... but it's kinda making me freak out that I'm gonna have blue toenails forever unless I quit working out! I'm rather fond of having 10 toenails... so I'd like for them to not fall off. Thanks!

Hi. I just discovered my left 2nd toenail has turned blue. Did you ever find out what might be causing it ?

Thanks