Your cat is definitely trying to tell you something. Now you just have to figure out what.
I would be very worried if it has been more than 24 hours since she last ate. Cats can experience hepatic lipidosis if they go without food. This happens when the liver thinks it's starving and starts to grab fat cells. This ends up killing the liver.
I suggest that you see the vet with her immediately (today if you can) so that you can get some bloodwork and find out what's going on.
This may be as simple as an upper respiratory issue that has decreased her sense of smell. Cats will often stop eating if they lose their sense of smell.
But at her age and with the symptoms you are seeing, I would be very concerned.