I have 13 hens who were laying between 9-11 eggs a day. All are between 8 and 5 mos. old. Everyone was happy and healthy until DH decided we needed 8 more pullets. About 11 days ago he brought them home and they looked healthy enough. My original 13 were flustered and dropped down to 6 eggs a day for a few days, then started to pick back up. But I think the new girls brought some bug with them, even though they all still seem healthy. DH swears he saw one of our black hens cough and throw up (do hens throw up??) last night. One of my Buff Orpingtons was coughing this evening, and one of my sex links was sitting in her dust pile and not terribly responsive at the same time. Both of those hens were shaking their heads hard frequently. Today we only got 3 eggs. DH just talked to the farmer's store and they said they sell an antibiotic to put in the water for upper respiratory illness. He's planning to pick some up tonight. We are completely new to chickens and are out of our league! Our kids are in love with these birds and I would hate to lose them. My son keeps talking about taking them to the vet, but...not to sound heartless, but hens are a lot cheaper than a vet bill. Should I quarantine the birds as they show signs of sickness? It seems like a moot point now... I am planning to sell at least four of the new pullets (since we'd have to expand our coop). I don't want to sell someone a sick bird, but how long of "healthy birds" should I give them before I sell them?