I just realized you feed Scratch and Peck. Do you ferment it, or feed the pelleted version? I ask because the powdery fines at the bottom of the bag/feeder is the added vitamis and minerals. Chickens sometimes don't eat these and a have problems. No idea if this is what's happening with your girl,but I thought it was worth mentioning.Scratch and peck layer. They get their own egg shells fed back to them.