From my research and experience with this, it indeed does sound and look like the classic Mycoplasma Gallisepticum (MG/CRD). MG is a serious life long bacterial infection of poultry. This disease is chronic, meaning that symptoms can go away and reappear at anytime, especially if they get stressed. All asymptomatic birds are lifetime carriers, spreading and shedding the bacteria from their feces, dander, feathers, respiratory secretions and other bodily fluids. I also highly recommend that you NEVER breed from your sick birds, because the MG bacteria can spread to the offspring from the infected parents to the developing embryo, making any chicks that happen to hatch, will be already sick with the bacteria and the cycle starts over again. It is best to keep a closed flock- meaning that you shouldn’t bring in anymore birds to your infected flock and don’t let any birds leave your sick flock. If you choose not to cull your birds, let them live their lives, until they pass away by themselves. I would highly suggest and recommend that you cull the sickest bird and send it off for a necropsy test. It is critical in poultry to get your sick birds tested because most of these diseases can be serious and/or fatal.
As for treatment options, there’s antibiotics you can use to treat the infection, but it doesn’t cure it as it is chronic. I don’t always suggest antibiotics because you don’t have a firm proper diagnosis, which is why I highly suggest that you get testing done to find out which specific respiratory disease is causing the symptoms. Antibiotics aren’t always a helpful tool, I’ve seen and read multiple stories about people who’ve treated their birds with antibiotics and it killed them. There’s also a lot of miss-use of antibiotics. A lot of poultry owners have noticed that most or all farm stores are removing antibiotics off their shelves, it is because people jump to antibiotics as if it’s a miracle cure, when really it’s not. Antibiotics can destroy healthy gut bacteria that helps the bird digest, by treating with antibiotics, it makes it so the bird doesn’t gain nutrients or weight, it actually causing them to lose weight and they’ll eventually die from starvation. I recommend that you start by using safe natural remedies for treatment.
Here’s two great places where you can either send out a live sample or a necropsy sample:
https://www.zoologix.com/avian/index.htm
http://www.vetdna.com
Here’s more information about MG:
https://extension.umd.edu/sites/ext... Mycoplasma gallisepticum (MG) Infecti....pdf
&
https://afarmgirlinthemaking.com/respiratory-conditions-poultry-mycoplasma-in-chickens/
I hope this helps!
