Cats do not have whims like people. Whenever they stop eating they are either ill or in pain. If her blood work was unremarkable and she has no other symptoms like fever, diarrhea, constipation, infection, etc then there is something going on that is difficult to ascertain - but it exists nevertheless. Sometimes a cat can have an abscessed tooth or root that is in the gum.They can ingest a piece of plastic that in not perceivable in an xray. They can be mildly dehydrated or have a metabolic or organic imbalance that is too slight to read on a test. She may also feel nauseated.
with a 7 year old, my first suspcion is an abscessed tooth or root in the gum that cannot be seen with the naked eye so the jaw should be xrayed.
A high white count is indicative of an infection somewhere in her system. A bad tooth, UTI or upper respiratory s possible.
If she had any recent stress, shots, procedures, etc her mmune system would be weakened allowing opportunist bacteria to enter.
High calcium may be a result of dehydration and that causes inappetite as well. She shou get SubQ fluds from her vet.
She may need a jump start when she comes home.
If your cat is not diabetic begin by giving her two droppers (cc size) of unflavored pedialyte every ten minutes for an hour. Next water down(plain water) canned cat food or baby food chicken or turkey with no onion or garlic and give only one dropper every ten minutes for another hour. Wait two hours and repeat both. When she feels hydrated she will lick up the gruel on her own.
Boil chicken or fish as the scent of food cooking awakens the appetite sensor in the brain.
Please discuss all this with your vet and let me know how things are going. I will stand by to hear from you and help further.I hope we can solve this mystery and get your baby back to normal.
I will always be here for both of you.
BTW: I am sure she did get the fleas there!