Have you taken her to the vet recently for a check up? May be worth just popping in with her.

I would suggest that you provide an extra litter tray say in your bedroom as she may not have time to find the other litter tray if it is downstairs or elsewhere. Sometimes elderly cats can lose their hearing and can be more vocal and "clingy".

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Kaz

For kittens, joy is for the asking and smiles are for the giving