Sorry to hear of your situation. I'm somewhat similar having metatastic Oropharyngeal cancer 5x, radiation 3x, and 3 neck dissections, two which were radical. Sounds like the cancer that was in the lymphs after the RND may not be the lymph's, which also happened to me, and is roaming cancer in my case. My treating hospital only wanted to give me radiation and chemo after my last surgery, but sought out treatment elsewhere. I found a doctor in NYC who is world renowned in Brachy, and especially HD-IORT, High Dose Intraoperative Radiation Treatment, which I eventually did. They did another neck dissection to take out remaining cancer, IORT radiation directly on the tumor site in the exposed neck during surgery in the OR, and then a pec flap for better healing, and so I could receive more radiation, chemo too, which I completed in November. It also depends on the amount of radiation each area received, measured in Grays (Gy) to get radiation again, and a few had gamma knife. I had a total of 130Gy, and few others like Kelly and Charm had more. Good luck with everything.