Anybody know anything about geriatrics?

Putting a feeler out there because this is a most puzzling and vexing situation:

My grandmother is 86 or so and confined to a nursing home. She moved in a little over a year ago. She does not have Alzheimer’s Disease or any form of dementia, but she’s got diabetes and Parkinson’s and she can’t walk due to a broken hip. Grandpa is healthier but quite feeble himself and lives in the home with her.

Four days ago my grandmother, from no apparent cause, suddenly went stark raving mad. As in, throwing things at everyone and cussing them out, threatening to commit suicide, repeatedly trying to escape from her wheelchair and the nursing home itself (this in spite of the fact that she can’t even really stand up on her own), accusing everyone of hating her and conspiring against her, refusing to eat or take medicine, placed on a 24-hour watch for her own safety, etc. My mom thought perhaps grandma had a urinary tract infection, which can make old people go a bit funny in the head. But then yesterday, just as suddenly as it started, the madness stopped. Grandma has returned to her normal character and started eating again and taking her medicine etc. Clearly, it wasn’t a UTI, or it wouldn’t have gotten better like that. Same with her diabetes, that couldn’t have been the cause either.

Everyone — Mom, doctors, nursing home staff — seems to be at a loss about this and we are all concerned this might repeat itself. This is a matter of concern for me, besides for the obvious reasons, but because whenever Grandma has a crisis Mom goes insane too and starts taking out her stress on everyone else and making their lives miserable, especially my father’s and mine.

Anyone have any ideas about this? I figure — anything y’all suggest can’t hurt, might help, and if it does help it will make a lot of lives easier, not just my Grandma’s.

UPDATE: Case closed. It turned out Grandma did have a UTI after all. Why she suddenly regained her wits no one knows, but now she’s on antibiotics to clean out her plumbing.