Well, I'm no expert by any means but I do know this much. You need to separate her from the other chicks. Give her her own heat source as well as food and water. You might try giving her crumbled egg yolk for strength. I know there a medications people recommend for sick chicks but I can't tell you what they are for the life of me! Hopefully, somebody will come along soon and tell you. I also know that a couple of tablespoons of organic vinegar and a crushed clove of garlic in a GALLON of water is good to help them build up their immunity. However, that being said, I'm not sure that's a good thing for chicks as young as yours. People???