Thanks!! My father is home today. He went and looked at the chicks. He said it's only about 5 that look like this, this one being the worst, or most obvious, since it's the only light one with the problem. He can't see any black debris. What I brushed off the chick I brought inside, it was white sandy like debris. Almost like crunchy dandruff.
I fell asleep and never made it outside last night to investigate. I'll set the alarm tonight! I'll send all the chicks into the lower pen with outdoor access. I think I have it baby proofed. Might be a little crowded though.