New chick, eyes swollen shut?
Perhaps she was pecked in the eye? Did she come from a feed store or a breeder? I would watch to make sure the other chicks aren't pecking her, and if so separate the guilty party with a little fence or box inside the breeder. I have seen new chicks peck eyes because they are bright. Usually separation overnight has solved the issue. If the eye seems to be draining, you can use Vetericyn eye gel or eye wash, or an antiobiotic eye ointment such as Terramycin. Those are available at many feed stores, but you may need to ask for them.
If you have any chick citamins with electrolytes, such as SaveAChick, or some pedialyte or even gatorade, you can gice her some, and dop her beak into the water as often as possible tonight and tomorrow. Sprinkle some chick crumbles around her feet. It might be a little hard for her to see until her eyelid goes down.