It may be too late, as she's worsened, but my 4 year old Black Australorp started fluffing up about a week ago. I've treated her for a vitamin deficiency before, but as the week progressed she started not moving around as much and now she can't stand. Her poop is normal, her crop feels empty, and she is not egg bound. She has gotten lighter and lost a lot of weight. She was eating and drinking a little until today. No signs of trauma or injury, she is just droopy and unresponsive. The rest of the flock is fine. No mites, scabs, mucus, or respiratory issues either. She has been sleeping all day and I've only gotten her to eat some bread. Now I'm having to force Nutri-drench water in her, but I fear she won't make it.