Sudden dental issues/lack of saliva

[happyhanneke]

I went to the dentist today. I have cavities and weak enamel close to my gums on my upper teeth. I need the cavities repaired.
I have white sticky spots as the dentist calls it. She also noticed I have very little saliva production which is likely the cause. She asked if I feel dehydrated I’m not sure about that. I am never thirsty so I can probably drink more.
I did start to take cynomel about 9 months ago. Can this be the culprit ?
This is a sudden change since I never had this problem so it must be something I do.

I’m throwing it out here since someone might have some suggestions. I am a bit down from hearing this.
I will do a search on this forum as well

Female 60 y/old