Why is my cat drooling? PLEASE HELP?

You say she's "recessive". Is that lethargic? With her tongue hanging out and a personality change, it could be so many things, injury, upset digestive system, poison, age, insect or animal bite. Cats are hard to self-diagnose. The vet is the best idea. In the meantime, just make sure she has access to clean water and let her hide out if she wants to--it will help to keep her calm.