Thyroid med and dry mouth ?

I use to get dry mouth from my depression medication during daytime. Chewing bio-tene gum sorted that out. Am now in England and increase in thyroid medication has caused severe dry mouth during the night. Prior to this the doctor gave me too much thyroid and I ended up in hospital. I cut down on the thyroid and the dry mouth stopped immedidiatly. However am having upset stomach. Is there a connection with the thyroid and upset stomach or just coincidence. pelmrussell