Nancy, I have dry mouth but only when I lay down for bed at night. The dryness is horrible sometimes and the roof of the mouth is so dry my tongue literally will stick to it. I have tried numerous tooth pastes, drinking water thru out the night, and nothing seems to work.
At least you are fairly certain a medicine is causing it, I have no idea on mine. I also have dry eyes during the night only.
I have been tested for lupus and other autoimmune diseases and my family MD had come up with no dx for it. The only blood abnormality I have is high iron.
I sometimes wonder if it is a food allergy, like maybe something like Saccharin, since I seldom have used regular sugar in years. But even when I used "Equal" sugar substitute, which I believe has no Saccharin, I still had dry mouth and eyes.
There are times when it does just the reverse, but that is rare, when the saliva just will not stop at night............
Sorry, no answers, just more questions.