failed root canal?

I had a root canal a few months ago and never crowned it as I ran out of insurance kind of unexpectedly.  The gum over the tooth never seemed to heal up quite right and to the tooth looks almost grey but I thought maybe this was due to the metal pieces they had to put in.  I just realized that the tooth seems to be a bit loose, can the root canal be failed?  There's no pain and I figured I was in the clear since it has been so long.  I think I had it done in March...

If it has failed, what would my other options be to keep from having a hole in my smile??