I had a tooth root canalled just over a year ago. In January this year I developed a fistula on the gum above the canalled tooth. My dentist removed the tooth at the beginning of January. I wasn't given any antibiotics and now two months later the pus filled lump keeps returning on my gum above the socket. I've been back to my dentist 2 times and both times she has said it's fine the pus has somewhere to go. How long before this lump stops developing?