Hey all. Last week my BCM pullet came down with gasping for air and some rales (rattly breathing). I had added 3 new birds to my flock after a 2 week quarantine. I started treating her with .5ml Tylan50 IM and she improved quickly. It now seems to be spreading through my entire flock so I have been giving them ALL (except the 3 new birds and 2 older hens which are showing no symptoms) .5ml of Tylan50 IM (the bigger birds I've been doing .75ml) Most are improving but I have one Brahma that I am VERY concerned about. I have been treating her with VetRX, force feeding scrambled eggs, and using a syringe to give her water. She can hardly breathe. She's skin and bone right now. She will seem slightly better for a bit, then quickly declines again. I do not knew exactly what I'm dealing with. Some birds also had one swollen eye and some nasal discharge. The main thing is the rales and sneezing/coughing. This brahma had thick clear mucus in her mouth yesterday and I actually used a syringe to suction her nostrils and mouth as best I could. Should I give her a little more of the Tylan? It's been 3 days and while others have greatly improved..she's not. Also, does anyone have any clue as to what I could be dealing with? I have a mixed flock but most are pullets that are around 14weeks (one cockerel and 2 white leghorns that are 2 years old are also affected). I know the birds I recently added were carriers as they are not sick. I did have my oldest EE hen come down with something similar last year and I treated her I believe with water soluble Oxytetracycline. I'm in NYS so getting water soluble antibiotics is a PAIN. Please help!!