Hi there....I can understand your concern. Do you any associated symptoms like dry eyes, increased frequency of micturition, joint pain, any chronic drug intake like antihistamines? There are many causes for dry mouth like anemia,
diabetes, sjogren syndrome, rheumatoid arthritis, any drug intake like antihistamines, diuretics, etc. Also you need to start relaxing yourself. Anxiety and tension also can cause dry mouth and fatigue. Try mediation and yoga to relax your mind. Also consult a neurologist so that he can evaluate you completely for dry mouth.