This is sign of rasa kshay on Ayurveda... Need to consult asap

'want of water' is expressed by the body in the form of thirst . Continuous excessive dry mouth called Xerostomia ,trishna roga in Ayurveda If u r taking too many medicine Or having anxiety Habits like smoking ,chewing tobacco and alcohol.it could be the reason Try to avoid mouth breathing Avoid excess sweets,keep oral cavity clean So observe this and work on the cause ...