Welcome, mlj ~
I'm glad you discovered the ANA website and the forums but I'm dismayed to read of your re-growth after almost a decade and now, pain following GK treatment to address the re-growth.
I'm not a doctor but I would offer the suggestion that the pain may be caused by swelling, which can occur for some time (years) following radiation treatment. I had FSR 3 years ago and occasionally feel some swelling (on the mastoid bone) that is uncomfortable but manageable with Ibuprofen. It usually dissipates within a few days. You might try this for your pain. It's OTC and if not taken in large doses, shouldn't cause any problems, but again, I'm not a doctor and could be mistaken. You might want to phone your doctor's office and ask if taking Ibuprofen is recommended for you in this instance.
If this pain persists, I would consider asking your doctor about steroids to help alleviate any possible swelling that might be occurring. He should be familiar with this and not have any reservations about prescribing the steroids, but that, of course, will be between you and your doctor. Whatever you chose to do, I hope the pain subsides, either spontaneously or with the help of medication.
Jim