Why do I have scarring on my fingers?

It's hard for me to remember but I used to bite the skin around my fingernails; not a lot though. Ever since, on a couple of my fingers it looks as if someone had dropped acid on my fingernails. The skin is really raw and bubbly and it's really visible when the skin is wet (it looks prune-y). But for some reason it will not go back to normal; it's been years. Does anyone have any ideas as to what happened or how to fix it?