I was diagnosed with the exact same thing last February. I underwent 35 rounds of radiation in six weeks from May to June 2024. First couple of weeks, I didn't notice any side affects. After week 4 my mouth and tongue were feeling burnt. By the end of treatments I had pain on the roof of my mouth and tongue as well as overall fatigue. I was taking Tramadol and Gabapentin for pain. Contrary to my doctor stating the worst of the side affects would peak 2 weeks after completion of radiation treatments, my side affects peaked at about six weeks. Drinking anything (including water) felt like razor blades at the roof of my mouth. Eating was very painful. Dry mouth is prevalent - you will be figuratively tethered to a water bottle.
Initially could only tolerate Cream of Chicken Soup (no salt) and that was with "magic mouthwash" to temporarily numb the pain. It was about 12 weeks after radiation treatments that I felt I turned a corner and stopped the pain pills. I lost 40 pounds, but I refused to go on a feeding tube. Glad I didn't!
I am now six months post treatment and have gradually added different foods back to my diet. I'm eating about 80% of what I used to. I cannot tolerate anything spicy as my tongue is still sensitive. Two months ago I resumed my usual fitness routine - 3mile runs four times a week and have gained my energy and stamina back. Exercising and nutrition for me is the two most important components of recovery.
I still have dry mouth, taste is coming back but still off. I developed Lymphedema on my neck/chin, which is swelling because of fluid buildup -my lymph nodes are not draining properly due to the radiation. I do some specific head/neck therapy exercises to reduce the swelling and it has greatly reduced my post radiation "turkey neck". Excess mucus is still a problem, although it has substantially reduced. I still rinse my mouth multiple times a day with warm water mixed with salt and baking soda.
Also, take meticulous care of your teeth as they will be more prone to cavities because of the lack of saliva. I use a prescription flouride toothpaste morning and night. Additionally, I floss and rinse (with warn water/salt/baking soda) immediately after I eat anything during the day - even a small snack.
Your recovery will take time, but everything gets better with time. Above all, keep a positive attitude and follow your doctors instructions/advice. Good luck!