Maybe this:
VITAMIN A DEFICIENCY
Depending on liver stores, adult birds could be fed a vitamin A–deficient diet for 2–5 mo before signs of deficiency develop. Eventually, birds become emaciated and weak with ruffled feathers. Egg production drops markedly, hatchability decreases, and...
Here is a thread I started when my chickens got pox in 2013:
https://www.backyardchickens.com/t/818895/wet-and-dry-fowl-pox-xxx-rated-graphic-pictures-of-pus-and-scabs
-Kathy
Edited to add:
Note that I only posted pictures of the most severe birds, many did not look that bad, lol.
When my peahen had a yeast infection her poop looked like this:
Note that this poop was from a hen with a bacterial infection, but it the one with yeast looked just like it.
-Kathy