Can Toenail Falling Off Cause Pain And Inability To Walk?

Hello,
A week ago I walked fast for about 4 hours, and afterwards I felt a slight pain under the toenails.
The problem that I have is that one of them is getting darker and darker.
After a few days it looked like in image1.
(I had to replace slashes with spaces because special characters were not accepted in the message).
Now, after a week, I feel no pain, but the toenail has almost become black as it can be seen in image2.
I read on the internet that the nail will fall and I would like to know what is going to happen exactly.
Is it going to be painful ?
Will it limit my ability to walk with shoes ?
How long will it take to recover ?
What special care should I take during recovery ? Should I protect this toenail somehow during recovery ?
Should I avoid walking ?

Thank you for the advice !

Image1:
http://imageshack.us/photo/my-images/836/img155h.jpg/
Image2:
http://imageshack.us/photo/my-images/641/img160u.jpg/