Opus is spot on. Isolation is the ONLY way to know what is going on with her. Her litter box and food intake will tell the story.
she should actually have her own litter box anyway, when litter box get a little too full with urine and feces cats have a tendency NOT to cover their elimination since there are so many smell they need not hide their scent.
Let us know what you observe now that she is isolated. Thanks
CML
Thank you for the advise. I might try isolating her to see how she is doing.
have you started using new litter by any chance? sometimes they don't like the feel of it...ie clumping vs non clumping or different texture.
If this were my kitty...I would somehow isolate her in her own room with food and litter box for a few days, so you are able to monitor how much exactly that she is eating. if her appetite isn't good than I would definitely say its time for a Vet check up
otherwise the covering alone isn't a reason to worry....but than again at 10 yrs of age, is when you often start to see medical problems arise and a full blood panel and urine check can be a very good idea
good luck