I could hardly eat anything during treatment. I lived on creamy mashed potatoes with butter. Cottage cheese. Egg’s anyway cooked, peanut butter and jelly , banana , power shakes with powdered supplements and boost , apple sauce, baby food jars, soups and noodles, Boost/ ensure cans pack a lot of good calories. I had to FORCE myself to eat. Salt throat rinse several times a day helps.Ask you Doctor about Magic mouthwash. It DOES get better a month or so after treatment. He is in a tough battle but it is winnable.