Grandma's blood pressure

My 85 year old healthy grandmother went to the hospital for a check-up yesterday and they said she had a little high blood pressure. She had it read when she first showed up for the check-up and it was high but then after being at the hospital for a little while it dropped 20 points. My Grandma believes it was because she was nervous. The last few days she has an extremely dry mouth and isn't able to drink enough to make it not dry. Today she was at her house and she felt funny and called my mother who worked at a hospital as a candy striper type. She read my Grandmother's blood pressure and it was 165/95 which was higher than at the hospital she is also hot and sweaty. My Grandmother never calls and asks to go to the hospital so today when she asked for my Mother to call and ask for help we thought it to be more serious. So far the hospital is just saying to monitor her. Do you have any ideas what is causing the dry mouth and do you know if there is any medication that might cause that. She is taking a few different types and some vitamins. Thank you.