Chloe is sick

I hope someone can shed some light on what is wrong with Chloe. She hasn't been eating like she usually eats and seems lethargic. Saturday morning she was limping - left leg. So I took her to the vet. Nothing noted with the exam, blood and urine are normal. They gave her fluids and an appetite stimulant.

We came home and she wolfed her food down. But she still seems off.

She has been throwing up - mostly hairballs. Her purr has become deeper. And she has an infrequent cough. She is not liking it when I pick her up. When I give her a treat - she seems to have trouble chewing it. The vet thought her teeth were okay.

Chloe is about 8 years old, strictly indoor, spayed and usually a delightful cat.

Any help would be appreciated.