I am new to raising chickens and don't know what the problem could be. I bought 4 chicks on Thursday, 2 RI Red and 2 Ameracauna. One of the Americauna today has started being very lethargic and is breathing heavily. The other three seem normal but this one just lays in one place with it head down, beak in the bedding, breathing heavily. When I reach in the brood tank, the other three run from me. This on does nothing. If I pick it up it chirps loudly, as if in pain or terrified. Any ideas what's going on?