Tami,
I had a similar expereince during my radiation treatments, not too much afterwards. I cut back myself and found that if I sit up, I feel better. Laying down gets the reflux going and more than a few times, I vomited. She should go to the doctor and see what they suggest. Prehaps prevacid, via the peg tube or something similar may help with the reflux.
Wish her well.
Jeff