I have 6 silkie chicks in a brooder. At 1 week if age one became really lame and just laid in the corner all the time. I would move it but it wouldn't run and it would use it's wings as like crutches to walk. Nothing is noticeably wrong but seems like something neurological or internal. All 5 others seemed fine. Just yesterday another one started the same thing. So I separated them from the other 4 but I figure more will start this. What does it sound like. I purchased these eggs from another breeder, they are not chicks from my birds and I have never had these symptoms before in any of my own chicks. Could it be mareks? Should I cull them and hope the others done get whatever they have? Thank you so much!!!