I had a root canal over 20 years ago in #19. 2 months ago I developed a periapical abscess and then a gum boil. I was treated with antibiotics and then 2 days ago had root canal re-treatment. How long before I know that the re-treatment is effective? Currently I have only minor discomfort and swelling, but the gum boil remains. Should the gum boil have resolved by now?