I put my 21 week-old pullet, Emma, to sleep today. X-rays revealed that she was crop-bound and no matter what we tried we could not suction all the debris from her crop. Today she vomited again and aspirated on some of the fluid. She had great difficulty breathing from that point and I elected to euthanize her and post her for necropsy at a diagnostic lab. Needless to say, I needed some serious chicken time today with the rest of my girls. When I went out to the coop I saw one of my wyandotte pullets and an ameraucana rooster sitting with their wings held away from their bodies (as if to aid in respiration). They occasionally would breathe with their mouths open and rarely, gasp or take a big gulp of air. These birds appeared completely healthy and normal while out in the yard (eating, drinking, foraging, pestering other chickens). When they sat still on their perches was when I noticed the respiratory effort. They have no discharge from the nostrils and I cannot hear any harsh lung sounds! They are 22 weeks old and only two have begun to lay (very small eggs). One of these hens is the wyandotte who looks ill. When I purchased these chicks I was discouraged from vaccinating them for Marek's disease since I have a very small backyard flock of 12. None have shown any neurologic or leg issues. It was warmer outside today than it has been (75 today vs. 65 last week) so I was wondering if they might be hot. When I noticed their behavior though, it was late and about 62 degrees. Also, these two birds are showing symptoms that are completely different from what Emma displayed! I am already about to lose it because of putting Emma down, but now I'm terrified that this could be Marek's or something worse and that I will lose my entire flock! What can I do?