Hi,
I suggest you talk to her pharmacist about the medications she's on and if there could be an adverse reaction to the combination of medicines. Also talk to her doctor about her sudden behavioral changes and your concerns.
Another possibility is that she's no longer taking her medications properly - too much or too little can cause all kinds of problems.
My mother's first noticable symptoms of Alzheimer's were clutter everywhere in her house, she forgot to dial "1" before long distance call, forgot how to make coffee, forgot how to set her clocks for Daylight Savings Time, forgot how to run her washing machine, and was confused about how to handle her mail.
It is important that someone in the family have "durable power of attorney" to handle her affairs and medical decisions if she becomes unable to do so. I was fortunate because my mother had the legal assignment of power of attorney made 10 years before I needed to use it to step in and handle her business.
I hope her problem has an easy solution and that it's not Alzheimer's. Good luck! Barbara