What would cause skin around toenail to turn black?

[grateful6982]

I had an ingrown toenail for about 3 months and now that the ingrown toenail is gone, the skin around the toenail has turned black and is really gross looking. I have been soaking it and keeping it as clean as possible, but it will not heal. Every once and a while it will develop pus and smells badly. What would cause this and how do I get rid of it??