Good news! My kitty's ok!
The vet just called and said she's not serious!!! He' s starting her on antibiotics and hopefully she'll improve.
I was worried we'd have to put her down since I've had to do that to one cat who was exhibiting litter box issues with his urethra, but she's female and he said she shouldn't suffer that problem. If the antibiotics/laxative don't work, then we'll do bloodwork.
Sooooooooooo...my oldest fur baby can come home!!