Hi @brad78 I posted a discussion about side effects of radiation a while back. here is the link: https://connect.mayoclinic.org/discussion/radiation-side-effects-when-will-they-ever-end/
Typically during and after radiation one can only tolerate a few foods, primarily soft or liquids for a while. I had broth, soft eggs, custard, porridge (oatmeal), cream of wheat, Ensure, and similar foods. Nutrition consisted of whatever could be tolerated. Regaining protein and calories was the primary goal.
You will find foods you can tolerate, perhaps foods you never cared for suddenly become favorites. Your taste will likely change. Swallowing may become a challenge. In fact it still is for me as I am often the last one at the table to finish. It's a "new" normal we all get to.
Don't fret about these changes. Don't be surprised about them either.
You may have an easy time of it, or perhaps not. We all are individual when it comes to this.
But to summarize, Eat what you can, when you can. Don't worry about a balanced diet. There will be time for that later. And keep active even if it's just a slow walk around the house.
I know this all sucks. Feel free to contact me anytime. I usually check this site at least once per day. I wish I could walk you through this, I really do. But you will be okay in the end and perhaps better. There is a saying something like "Scars have better stories than tattoos".
Courage.

Hello @brad78 . I had SCC in an ear, temporal bone resection, paraotidectomy, neck dissection almost 12 years ago at Mayo. Radiation/chemo followed due to not clean margins but I did that at U. of Michigan closer to home. The nutritionists there were quite helpful but encouraged any form of calories during the 7 weeks of treatment so high sugar shakes were a mainstay. Since then I did really modify my diet due to new normal taste preferences and research into reducing sugar and increasing protein. I seem to crave vegetables especially now. I was quite a sugar addict before but found it pretty easy to decrease that consumption. I save my sugar intake for dark chocolate now, and Manuka honey. I found a book by a Mayo palliative care MD very helpful in many ways including diet. "How Not to be My Patient" by Ed Creagan MD. You can get it thru Mayo bookstore or on Amazon. I loved this book so much that I bought copies for all our kids and other family members. How are you planning to change your diet?