Hi Kathie,
I also have extreme dry mouth from two rounds of treatment of both chemo and radiation (70 radiation treatments in all). My salivary glands were completely destroyed. I was unable to swallow for several months but can swallow now after months of swallowing exercises, a small surgical procedure on my esophagus and dilating my esophagus several times. However, the condition of my mouth (not just the drying but all the cells on my tongue and the whole interior of my mouth are out of balance) feels horribly wrong all of the time.
The only thing I have found that helps is swishing my mouth with Biotene mouth wash and spitting it out. I also do this constantly (not every minute but frequently). Sometimes when I am sitting quietly, not opening my mouth or exerting myself in any way, I can go for a half hour or so without swishing my mouth, but if I am talking or walking or really doing anything at all, I must swish my mouth more frequently.
My heart goes out both to you and your sister.
Patricia