There is a red heat lamp that I moved off to the side. Poop doesn't look red to me. But some is a bit looser than others. So I will treat the whole flock for Cocci?
If any of the poop have mucus, which it looks like some might, I would probably start Corid. That spec of red I can see in the picture doesn't look like the red reflection of a heat lamp, it looks like it might be blood or intestinal lining.