I have a small flock of juvenile chickens and I've had a few suddenly come down with an ailment. The first sign is that a bird moves and walks slowly then seems to pay no attention to anyone approaching it. They'll just stand there like they don't have a care in the world then eventually separate themselves by finding corners or staying in the coop. I've had 2 Ameraucanas, 1 buff orpington and 1 of my french blue marans do the same thing then die. After the first one caught my eye I started separating birds that act that way immediately but they'd die then another bird would show signs a week or 2 later. All that said, my birds are free ranging on about 2 acres but I keep everything as clean as chicken housing and bedding can be kept. My aunt has several other birds next door that have come over the fence but none of hers have shown any signs and this has been an issue the past 2 months. Does ANYONE have any idea what this could be and does anyone have any experience with treating it? I've tried VetRx but that didn't help. Also, each sick bird was a hen and neither of my roosters has ever missed a beat...Thanks in advance.