Not all but at least one of them has mildly labored breathing and sneezing.
How old is she?She is also withdrawn. I'd like to nip it before it gets worse. I'm thinking something in the water would be good but that would mean treating them all.
She's about three yrs old.How old is she?
Could there be another reason for the labored breathing - crop not emptying, fluid in the abdomen, canker/lesions inside the beak...
Check her out really well. If you feel she needs an antibiotic, then I would only treat her if she's the only one showing any symptoms.