Yes it's very possible that the jaw issues are related to the radiation. I get pain along my jaw too, sometimes it's just from swelling in my cheeks, (I'm under 5 months out. ) sometimes it can cause fibrosis, and bone necrosis. or maybe just nerve issues. If the Drs can't find anything it's probably related to the radiotherapy. I'd she have a neck dissection. I find fluid build up makes my chin hurt at a certain point. Good luck and welcome!