To AdrockTN ....
Sorry to hear you are going thru this and watching a rapid decline in your grandmother. Could it be ... the passing of your grandfather a month ago has triggered the rapid decline of his partner in life?
My Mother has had dementia for an unknown amount of years, but it was officially diagnosed close to three years ago. I believe she is going thru the stages of dementia in more of a normal timeframe .. that is, over a fairly long period of time. Changes of medication, however, have seemed to have started physical changes in her - the latest one of being confined to a wheelchair nearly all of the time.
I wish the best for her ....... and for you and yours.