Please give the vet a call, as soon as you can. Something is going on with her, whether physically or behaviorally. Has something changed in your household routine?
What with the Labor Day holiday, are the regular vets closed for the long weekend? Do they have an emergency number, or can you leave a message for them about what's going on and maybe someone checks the line who might call you back before Tuesday?
Meanwhile, I'd say give her some space. Keep up your regular routine of feeding and scooping the litter and cleaning things up, as calmly as you can. Don't act scared of her, but let her approach you if she's friendly. And if she's in attack mode, stay out of her way. If you give a stern "NO!" and move away when she starts acting up, will she hold back?
I wish I could wave my magic wand and make things all better! My kitty Sparkler and I are sending along loads of loving good wishes and warm healing energies to you both. Thank you so very much, from the bottoms of our hearts, for bringing this scared girl in, welcoming her Home and working so hard with her and loving her. Blessings to you all.
{{{{{HUGS}}}}} and ~~~~PURRRS~~~~ and :love::love::love::love::love::love::love::love: from Pat and Sparkler