Hi Bad Kitty,
Welcome to OCF and I am so sorry to hear of your cancer and ongoing problems. As Chris noted, I had surgery and radiation about 5 years ago for stage 4 on my tongue. I had to learn to be very patient with radiation recovery. For reference, it took over a year before most flavors felt close to normal. Some, like sweets, I got back in a few weeks/months. Spices and complex flavors took much much longer.
As for swelling, infections, and pain, keep staying on top of it and communicating with your doctors. Find anything you can process best you can and focus on jamming calories. Mixing with a blender or Vitamix (think OCF gets a discount) can help. If you can not do liquids, which yours has gotten that bad, you should stay in close touch with your doctors and consider a PEG tube or nasal feeding tube. I had a nasal feeding tube after surgery. It was a pain but it worked.
I was fortunate and only had minor infections during radiation treatment and was able to keep processing food even though most of it tasted like dirt. I tracked my calories trying to hit at least 2000/day. I would give myself a small treat (favorite walk, favorite snack, etc) if I hit my numbers.
Please keep us up to date. Stay safe and keep the faith. Better days are ahead and we are with you.
Nels