My biggest fear is what you just described. We have hawks above. 2 teen chickens. They hide behind the bushes camouflage. And I think it gives me a false sense of security, but they just hate being cooped up. My teen rooster runs his beek back and forth on the metal screen till I let him out...
I had a farm vet come out twics, she tried two different, unsure which as I'd never had sick chickens before. Injection and drops. The drops from tractor supply I tried first, VetRx also. Nothing touched the respiratory that moved into huge pockets under their eyes until I used Collodial Silver...
Colloidal silver drops in the eyes and water. That was the only thing that cured the respiratory. No antibiotics worked, not even from house vet call.
Drops in the eyes, as it goes direct to the issue.
Give it 48 hours. 3x a day a day and in water.
13 weeks old, from a farm in PHX, no crowing yet, Black Marans of Olive Egger (all black slight copper on neck and 2 white spots rear), and my mystery fella (I think has Marans, feather feet but puffy cheeks) Amaracana. No pointy neck feathers on the grey one, but acts like a roo, bossy and...
Colloidal Silver drops. They are the only thing that seem to work.
I even used them in the eyes of my chicks and it was the only thing that got rid of a serious respiratory infection. Antibiotics didn't work at all...