Debra,
The symtoms your Mom is having are also symtoms of the growing cancer itself.
My husband is a new Stage IV patient and I'm learning all I can also. I don't know it all.
My husband doesn't want to eat either, but I'm giving him the high-calorie, high-protein drink powder that body builders use to gain weight. So far he can tolerate it, like a milk shake, and his weight loss is slowing down. No gain yet, however. He drinks 3,000 calories a day of this and eats what he can.
As for the nausea, do you have Kytril of phenergen suppositories? These have both worked for us. The urge to vomit does not entirely go away, but it lessens.
Encourage your Mom to eat what she can; puddings, jello, canned fruit is softer, toast with p-nut butter, basically anything, try anything.
I don't think you should blame all of her situation strictly on the radiation, but I don't know those details for you. It was certainly hard for my husband..Did you have radiation directly to the lung?
What chemo did you have?
Her stress can cause her more problems with respect to her healing. Give her as much anti-oxident supplements as you can. Life Extension Magazine has suggested doses for cancer. Watch funny movies with her; go into the garden, have meals with candles in the dining room, not in bed. Do whatever she agree to to change her mood of depression.
I know it's hard; it's hard on all of us as caregivers. However, I find that the more positive both you and the patient are the better you seem to advance in this race.
I hope this brings some calm to you,
aly