My family has a strong history of Alzheimer's Karen, I sure feel for what your going through.
I sure hope it's just a complication from meds.
It's so frustrating for them, while most times dementia is a gradual decent, my Grandfather had it but we didn't know it was so slight. Then one afternoon he had a heart attack out in the garden, and when he can through at the hospital and woke up, the Alzheimer's had progressed by years, and the Pop we knew was gone. Over night his mind was gone.
He went from forgetting where he was going to not even knowing who we were.
He lived for 3 years after that, and all his siblings had it. One of his sisters lived for 8 years like a baby with it.
My heart goes out to you and your family.