My family member with dementia was at the time of placement reasonably ambulatory with cane or walker. Mentally engaged. Recognized family members and others routinely involved in her daily life (caregivers, neighbors, etc). She was moved to NH (3 weeks ago). I went to see her on a Friday, Tuesday went back to find her slumped in wheel chair, no longer walking, not engaged at all and did not appear to recognize or respond to me. She is and has been for years not able to articulate, so is non verbal so I cannot ask her about herself. I am concerned and frightened by the sudden change. My imagination and guilt for putting her there is running rampant. Is this sudden change a normal progression or could there be something more sinister to her decline?
She could easily have suffered a stroke and that's why she's no longer ambulatory and you're seeing such a decline. Not to mention, dementia can progress rather quickly, even if she didn't have a stroke, so that's something else to consider, but I'd be inclined to think stroke myself.
Good luck!
You could mention this to the staff and have her checked for a UTI or possible TIA.
And yes, people can change that rapidly.