Infection of bone. Life long infection?

I visited my usual dentist after she told me to get a root canal for my tooth. I kept pushing it and chickened out till recently, I went to her for the root canal. I was travelling in 3 days and asked her if going in for a root canal was a good idea, she said it would be okay and I can finish the entire procedure in two sittings. They used a medicated cotton and sent me back and told me to come after 2 days. When I went in again, the doctor said I had an infection used medicated cotton again and put a temporary filling. The pain has been continuing for far too long even after consuming antibiotics. I'm supposed to go in again today for my 3rd sitting and she said use of Anesthesia depends on how infected my tooth is. I think the infection is already spreading, I can feel the pain radiate through the other teeth on my left jaw. How soon will I recover? How long will the pain last? What sort of infection is it? Is it a life long infection? Please help.