HI there... I would push to have them look at the node. It could very well be reactive but better safe than sorry. Usually a sore that doesn't heal is one that needs a biopsy if you're experiencing cankers and they heal that's okay, but the ear pain and node need to be dealt with - even if they are benign. PETs a great but I think - much like the others - MRI and CT - they only pick up tumors of a certain size and can't "see" microscopic cancers - also the results are only as good as the radiologist reading them.

to ease your mind, ask for a referral to a top ENT within the treatment center you were treated at - hugs.