HI,
can you drink liquids? try warm water, or weak tea. I find warm liquids really thin the flem and push it down.

Also, use less per can at a time (slower rate). Down to 104 lbs is pretty low, so I know you don't have a lot of "spare" weight. Maybe try fewer cans per day, or slower feed rates in the hope that what goes in can stay in.

Is there a muscle relaxer medicine that might control or limit the gag reflexes?

Just take it week by week. Rad's almost done, and will be tough for a couple of more weeks but then should be getting better.

I didn't have a PEG, but did survive on a few cans a day, or a yogurt, or a glass of soy milk. It should get better soon.

I had trouble with coughing & thick flem, cough syrup (codiene) helped me. Would it help thin the mucus for you?
good luck,
michelle