Mycoplasma gallisepticum & infectious bronchitis. Well I did what this site always warns about. Bought 5 beautiful healthy looking birds off craigslist and did not fully quarantine. Noticed sneezing in a couple of new birds, and within 2 weeks my original birds are sick. Sneezing, depressed, fever, some with rattling breathing and one with a big puffy shut eye. Brought the 2 sickest to the vet and had all test done to find out what I was dealing with. Have now been on Doxycycline(sp?) antibiotics and all have survived, but vet warns my flock will always be carriers now and it may come back in times of stress.