My guess and just a guess it started around tonsils as u say and spread to the lymph nodes . The ENT scope should find the tumor source. It is not so bad and they can numb you. I choose surgery but as I understand the HPV16+ responds very well to radiation alone as in shrinking the tumor. They usually remove all lymph nodes on the side of the neck they are working on and send to lab for testing to make sure none have cancer.