Hi, Sweety,
I know, they tell you you should keep your weight up while you are throwing up and can't swallow anything. It is a battle!
Milkshakes and those ensure type drinks, if you can stand them (they make me sick even though I can't taste them) are the best stuff I can suggest. I have lived on yoghurt smoothies for over a month, and lost about 30 lb in three months. I think the yoghurt also helps to keep your mouth healthier - look for the kind with live cultures. Some people can't eat them because of the acidity burning, but I have not had that problem - avoid the kinds with citrus fruit.
Things are getting better for me (almost 4 weeks postradiation) but I still spend most of the day eating - very slowly.
I never had a PEG, but do talk to the dr about one, it can be a lifesaver.
Lots of luck, Leena