I am really sorry you are experiencing such difficulity. I want to welcome you to Neruo Talk, and maybe say a few things regarding the problem you have.
My father had that same cancer in his throat, so I know a little about the radiation treatment you had. I am not sure if I were in your situation I would give up just yet about having that tooth extracted. Living with a permanent infection will lower your immune response. This can't be good for the all over well being of your body. Do all of your doctors, your oncologist, PCP, and Oral surgeon all agree? There are also degrees of specialities within the oral surgeons themselves. Maybe you can do a little research on line for specialists in your area. I do hope you will contact Bryanna. She is the most knowledgeable on this site about dental issues. Please post to her. I know your situation is serious, and I do care. I will be here to listen, and would gladly help you with research if you need me. I really hope you can find better resolution than what has been presented to you. ginnie