Do you know anyone who might have a little more cat experience than you? Maybe you can call them. It really sounds like either a cold, or depression. Try to get kitty to play, and see if that doesn't help, they love feathers. Try some milk too, see if that works. Hope this helps, good luck to you both.
Your cat's signs are quite vague and can be caused by a number of problems. If your cat does not perk up, move around, start eating or drinking in 12 hours she needs to be examined by a veterinarian. Try to keep her in a quiet space like a small bedroom, bring her food, water, and litter box to her. Also tempt her appetite with canned cat food, tuna, and chicken. Flavor her water with a small amount of milk, tuna juice, and a little bit of ice cream. Dehydration and anorexia in cats can have serious secondary complications regardless of the cause and need supportive care.
If the cat is eating and drinking, I would think the weather could be the reason she is away from you and quiet, My cats do the same thing, They are not around other than in cool places, but they are eating and drinking, having said that, some cats do eat less in warm weather. I would try taking her drink and food, but if it goes on for 24 hours or more, then seek a vets help, it can be a few things but you do need to watch your cat. Don't let her dehydrate, she must drink .
Under the weather doesn't prevent a cat from using the litter box or drinking water. It sounds more serious than that. Obviously you have access to the Internet, try Googling online veteranary assitanse for your county or state and describe the issue. Ask what you can do to get through the weekend until you can get in to see your cat's doctor.
