Radiation is different for everyone but USUALLY you will have a return of taste. I was only radiated on one side (tonsil cancer) but I went through a cycle of food tasting weird, then bad, then like cardboard, then back to weird...at one point everything tasted sweet-even my water tasted like sugar water. I first noticed the changes when cheese tasted awful.
The bottom line is to roll with it-find liquid nutrition to supplement your caloric intake. It can sooth the mouth also. My tongue and one side of my mouth was horribly ulcerated and it actually got much worse after radiation treatments ended and the cumulative effects continued on. If it get so bad that you are not eating or drinking then ask your doctor for cetacaine-it is a spray the will numb your mouth for about an hour. It can hurt right after application but it was nothing a few laps around the house didn't take care of! :-)
Find a brand of supplement like Boost or Ensure to make sure that you are getting the energy you need to heal. I also went to the local GNC and got a protein powder that I mixed with milk, fruit and ice to make a delicious smoothie that was high in protein. Your need for protein is very high now if you are going through radiation.
It has been 3 months since the end of radiation...things taste better but I can't eat everything I want to. Just when you think things can't get any worse you will begin to feel better-it happens quickly. Then you will hit a plateau tha may last for up to a year. I will celebrate with a big cheeseburger and some orange juice...both things I can't eat now.
Good luck-keep trying new things IN MODERATION and track your reactions. I am now eating salads and I can dip chicken in ranch dressing. You didn't mention whether you still have salivary glands-moisten all your food and eat small pieces slowly. Enjoy what you can and dream about the things you can't-you will get there someday!