The most important thing to do is take her to the vet, as others have said. Your vet can help you more than any of us can.
Aside from the obvious:
-Keep the pup warm
-Get the fleas off ASAP, Dawn dish soap was a great suggestion.
And I would like to add something myself,
Young chi's are at risk for low blood sugar, and with mine she didn't want to drink her water. My vet suggested to fill a syringe with sugar water and give it to her that way, the sugar helps her blood sugar level and the water obviously hydrates her. Another thing my vet suggested, if you notice that she misses a meal or doesn't want to eat a meal you have scheduled for her, keep some honey handy in your house and either rub some on her gums or let her lick it off your finger. This will help regulate her blood sugar level after missing a meal.
For future reference, make sure that any time you get a puppy that it's from a reputable breeder, signs of a good breeder are:
-They are willing to drive a certain distance to meet with you
- They make sure your house is a good home for the puppy, and if it isn't they will not sell the pup.
-Come with first set of dewormer and boosters
-Are willing to take the pup back at any time if it doesn't work out
-Has information on both parents and the pups bloodlines, along with papers.
-Some will have you sign a contract
Hope that helps! Let us know how everything goes if you can, and please try to get her to a vet!