Gims, I would make an appointment with an internist in another town. Bring the list of medication she takes and not mention any of your suspicions, so you won't influence him. It is very possible that her medication dosage has to be changed every once in a while. Hopefully that is the reason.

I would also speak to other families that have their parents there. Just hear them out and not tell them of your own suspicions.
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As soon as you trust yourself, you will know how to live.
Goethe