@abdulhamid50, I wonder if any of these related discussions might offer helpful suggestions for you.
- Dry mouth remedies: https://connect.mayoclinic.org/discussion/dry-mouth-remedies/
- Wake up with dry throat at night. Suggestions? https://connect.mayoclinic.org/discussion/dry-throat-at-night/
- Dry mouth: Any ideas on how to help?: https://connect.mayoclinic.org/discussion/dry-mouth-2/

According to this article "High stress and anxiety levels can stimulate the stress response in the body, which often alters a person's sense of taste. Anxiety can cause dry mouth, which frequently results in a bitter taste."
- Bitter taste in mouth: Symptoms, causes, and home remedies: https://www.medicalnewstoday.com/articles/321175

Are you experiencing high levels of stress around the same time as this started happening?