Gatorade, pedialyte, or water with a little sugar can also be used. Do you provide grit for your chickens to eat as they need it? She could be having a reproductive issue, infection, worms or even coccidiosis, since she is new on your soil. Corid can treat for coccidiosis, if you think that could be an issue or cannot get a fecal float done by a vet. Worming can be done with Valbazen or SafeGuard Liquid Goat Wormer or horse paste. An antibiotic such as Fish Mox amoxicillin could help if she has some infection. Reproductive infection or internal laying issues are vety common in hens. I would just try to get her drinking and eating. Check her crop in early morning to see if things are emptying normally. With a puffy soft crop in early morning, sour crop might be a problem if her beak smells sour or bad if you massage ber crop. A slow crop can happen when they are having reproductive issues.