I think my chicken has diarrhea? (gross picture warning)

[Missespenaloza]

This is a new chick who is about 5 weeks old? I got him 9 days ago and he started out with really liquid, stinky poop. I've put some ACV in their water and he is still pooping very soft wet poop and it shoots out of his butt. It doesn't stink anymore, but I'm not sure if I should be doing something else. He is with the two other chicks we got with him, but is otherwise mostly in quarantine until I figure this out. Is this diarrhea? How can you tell? I haven't seen him make a solid looking poop at all, but I haven't stood there and watched him for hours, either. The brighter picture is last wednesday and the other one is last night.

 

[Eggcessive]

Are you seeing any blood in the poop? Sticky and smelly poop is possibly cecal poop from the cecum in the intestines. Since one of those is in red light, it looks red. If there is any blood, I would treat the chicks with Corid for possible coccidiosis.