She needs to be seen by a vet- she doesn’t look like she eats well.. she could have fleas(if not treated they will make her anemic), check her bum if she looks like she has diarrhea, maybe she needs a test for giardia a parasite that causes diarrhea and she could also have worms.. are her eyes clean? Or watery? She could have cat flu and fever.. trust me with a simple vet visit- they can give u the correct medication and this baby in a week can be brand new.. without medication- the way i see her eating- she won’t survive… give her a small shelter with a blanket if possible to be kept warm, and if you are able to give her the medication she has a chance