Whatever the doctors tell your husband to do as far as swallowing exercises, jaw exercises, Aquaphor on radiation site, salt/soda mouth rinses, etc. encourage him to do. I feel like that helped me come through my treatments in better shape. I drank lots of Ensure, Carnation Instant Breakfast, Boost, Special K protein, water, shakes, ate lots of ice cream and my husband made many trips to the grocery store trying to come up with things I could eat - I did not need a feeding tube because I was determined to eat/drink and not lose too much weight. Sometimes it took me awhile to get things down but I did it. Don't take it personally if your husband gets cranky when you encourage him to eat. I knew I needed to eat but I didn't feel like it and with my husband telling me to eat, it just reinforced what I didn't want to do but knew I needed to do.
It helped me to know that I would still feel crummy at least 2 weeks after treatment ended.That way I wasn't thinking that everything would be rosy as soon as my last treatment ended. I was able to taste some food about 6 weeks after ending treatment. It will get better, just keep that in the back of your mind.