I have a staph infection in my knee . I noticed it has white pus stuff in it, but it won t just wipe off- it s really sticky and hard to get out with tweezers. I finally got a hold of it and when I went to take it off, there was a big hole under the infection. I left it alone, and covered it, but is this normal to have a hole under where the infection is? Should I keep the hole clean or just leave the stuff alone?