@alberth
I lost 20lbs during radiation treatment and had not much of an appetite during the latter stages of treatment. Drank smoothies with ice cream for calories and tried my best to eat something to keep weight loss to a minimum. I think everyone experiences a lack of appetite at some point, between physical symptoms and the mental stress that comes with cancer recovery it no wonder why one’s appetite suffers.
Biotene mouthwash and two Xylimelt tablets were a big help in combating dry mouth symptoms during and after radiation. As my saliva has slowly increased I’m doing a tablespoon of extra virgin olive oil and one Xylimelt tablet at bedtime (otherwise symptoms are manageable during the day). The extra virgin olive oil has poly phenols that are good for your immune system and coats the mouth and throat.
You will get better…

@alberth my husband went through treatment in 2012 and lost so much weight they finally put a PEG tube in because he wasn't able to swallow. I half joked that he was saving us grocery money because the liquid supplement he was prescribed didn't cost much. He just had to put that stuff down the PEG tube 3X a day.
The only issue was that after the GI doc removed the PEG when treatment was finished, he had to do esophageal dilations several times so my husband could eat solid foods again. He still lost almost 100 pounds, but he gained most of it back as he healed.