Hi, Hannah. I don't have answers, but I have some questions which, if you answer, will help our experts to help you when they come on, probably in the morning.
So. How old is the hen you suspect dropped this poop? What do you feed, including treats? What antibiotics and anti-inflammatories are you giving, and how long have the hens been on them? How do everyone's combs look? Check for color. Is anyone pale, dark, dusky or bluish? Is anyone's comb floppy? Nobody has nasal or eye discharge?
I can't think of anything else that may be pertinent right now. Thanks and good luck.
Sorry, typos