hi folks I have 4 chickens 2 seabrights and 2 ameracuana mutts. the mutts are about 7 months old, and the seabrights are 4 months old. One of the ameracuanas started showing respiratory symptoms along with constantly looking sleepy within a few days since we got her. we tried to isolate her, but one of the seabrights soon started showing symptoms, and now we have 3 birds showing respiratory symptoms and lethargy/sleepiness. One of the ameracuanas has been totally good even though she's been in contact with the other infected ones. the sick girls have been up and down for the past 2-3 months. The sickest seabright was okay for a bit and then started constantly sneezing, and now she has a terrible swollen sinus. The ameracuana just shows lethargy, and has been laying eggs with no shells, and having trouble with leg weakness overall. We did a culture at the vet for the seabright, and it's been almost 1.5 weeks with no results. she gave my little seabright an injection of doxycycline, and also asked us to inject Naxcel twice a day. She looked perkier, but the sneezing didn't go away. And now there's that terrible swollen sinus. I am wondering if it's even worth trying Tylan 50 on chickens who have been sick for so long. if yes, what is the dosage for a not fully grown seabright? I understand that this could be CRD and many folks cull their sick chickens. I'm trying at this moment to see if I can clear up her symptoms and not cull. please help. I am so confused and discouraged. I've done a lot of research, and its making me crazy. They are mostly free range chickens and we try to give them the healthiest diet that we can.