I'm sure I've seen this before, but since I'm currently BFuddled, I'll ask now... One of my little ones (3? wks old) has loose watery poop that is a lovely shade of yellow-ish brown. This little one eats, drinks and is active, but prefers to hunker down with one of the bigger ones (6wk old Ameraucana) and NEVER shuts up (already posted this). She has bouts of pasty butt and isn't as hearty or as big as her "siblings". She was originally the largest of the 3, but hasn't kept up. She also has ENORMOUS wing feathers that she can't quite get folded back all the way (I think she hatched with them!). None of the other 4 have icky poop, and seem quite healthy and tolerant of "Super Sonic" chicks fragility and need for warmth. I've been putting ACV in one of the waterers, and left some yogurt for "free play", but haven't seen any improvement in the littlest one. Any idea what this is, how to treat? Thanks for reading and any advice.