I have some sick Silkies. I have a flock of 22 hens and chicks. 9 chicks from this year born in April and May. I lost a hen 2 weeks ago, and 2 days ago I lost my beautiful rooster. For about 2 weeks, 1/2 of the flock have had olive-green gelatinous poop. I have also found black tar-like poop and...