This is Dr. David
I am sorry you have not be feeling well for so long.
dry mouth can come from you not drinking enough fluids or possibly sjorgren's syndrome.
which is an autoimmune condition when your body makes antibodies and attacks your mucous membranes.
or it could be from you sleeping with your mouth open at night? this can be from sleep apnea and severe snoring.
do you have severe snoring or sleep apnea? when you don't sleep well and wake up with intermittent sleep so you can't rest?
this happens more in patients who are overweight