When I brought my chicks home from the feed store, one of them was open beak breathing, very lethargic, and sneezing. I thought we were going to lose her but now she is almost 14 weeks and one of my biggest hens! The rest of the chicks all were sneezing too after awhile. I changed the bedding almost daily. I think it was just because of dust too (the brooder was in the garage). They all ended up fine though
It's been awhile but I wanted to update you all since you took the time to respond before.
Millie has recovered and is doing wonderful. About a week or so after my last post she stopped all symptoms. No more head shaking, no more breathing hard. None of the other chicks got sick and she never got any worse, so I'm thinking she had something stuck that eventually worked it's way out as she grew.
Her and her sisters moved out into their coop/run today and they love it.
I want to thank you all again for helping me diagnose her and all the advice you gave!!