Re: Black and blue toenail won't fall off
A black and blue nail IS a pool of blood under the nail. Apparently you released it by poking. If you release the blood soon enough after the injury, it's actually possible to save the nail, but a week and a half is usually too late.
Leave it alone and wait. This is the nail on your big toe? Then it'll take a long time, months, for a new nail to grow in underneath. But one day it will, and your dead nail will fall off, and then you will have a healthy toenail again.
To prevent infection from getting under there, wear clean dry socks and don't go barefoot in public locker rooms.