Tooth abscess and root canal re-treatment

I had a root canal done on tooth #29 about ten years ago after an injury to the tooth. All seemed well until I noticed a swelling under this tooth a few weeks ago that hurt when pressed. I called the dentist and was told I had an abscess. She prescribed me 150mg Clindamycin every six hours over ten days for the infection and referred me to an endodontist. The endodontist retreated the root canal a couple weeks later. A few hours after the retreated root canal became horribly painful and I noticed some swelling. The swelling continued to intensify and spread to my cheek. I called my endodontist and he prescribed me amoxicillin (500mg every 6 hours). The next day I went to the endodontist and they made an incision to allow the abscess to drain. I was also given a prescription for metronidazole (500mg every 6 hours) to take in addition to the amoxicillin. Thankfully the swelling in my cheek subsisted, however I still have a fair amount of swelling and tenderness in my gum under the retreated root canal and my jaw hurts a little. My questions are as follows...how long should it take for the swelling and tenderness in my gum under my tooth to go away? Is there any chance of this infection spreading to my cheek again as I am now finished with my antibiotics? Should the tooth be treated again or extracted? When they open the area again to permanently seal the root canal or do any other work is there a possibility of the infection spreading?