Drooling and breathing through mouth

This is happening to my cat right now. Yesterday she was hiding all day and today we found her drooling and breathing through her mouth. My dad called the vet but it was closed so he calle the animal hospital about 30 minutes away. Theysaid to let her be for awhile and put her by water. And to bring her in if she is still sick later. We also have a new kitten but we have had him for about 5 months though. They are both fixed by the way. They don't get along though, they always fight I'm so worried 

How is your cat doing now?