Two months ago we got 2 pullets to add to our flock of 3 hens, aged almost 3 years. We quarantined the new ones for 4 weeks, so they've been integrated for over a month. 2 weeks ago one of the older hens got a droopy comb and was acting lethargic, including sitting in the nesting box for hours. I didn't see mites, she was breathing OK, her crop was fine, eyes clear, poops looked normal (although I couldn't tell which were hers). She had been laying frequent soft-shelled eggs for the prior few weeks. I felt inside her and found an egg (hard shelled) and followed instructions for egg bound chickens, but she died within 48 hours. I concluded she had a reproductive problem/infection. Now Cleo, another of the older hens, is acting sick. She is lethargic and went into the coop to roost in the afternoon. I have isolated her. I haven't examined her closely (it's dark now), but does anyone have any suggestions of what to look for or do, assuming she has whatever the other chicken had? Could the new chickens have brought something in, despite being quarantined earlier and seeming healthy?