I had dry mouth for years, then dry eyes and have found out in the last 2 years that I have Sjogren's syndrome. It's not all that common, but can cause grief for years and drs. don't always test for it. Probably not your problem, but be aware of it. I also lost 2 teeth due to dry mouth, and the dentist should have been aware of it.
Good luck, PS. Use Biotene gel around your gums when you go to sleep, helps some. Ginger