About a week ago, one of my chickens died from egg yolk peritonitis. The vet also mentioned that she had perisites (didn't spell it right, I know) Now, one of my other chickens is making weird sounds and pasting up like crazy and is all poofed up. And my mom said that she noticed another chicken acting strange. What could be the problem! My entire flock is dropping dead! Could it be perisites?