Sick Hen - green poop

[StarryBayFarm]

One of our chickens is showing signs of being sick. She’s in the run alone tail down and droopy comb. She has green poop coming out her butt. How do I know what to treat her with? Should I isolate her now?

 

[Sally PB]

Please get some pictures of her poop. No, we don't think it's gross, it's helpful to see it.

Also, what do you feed her, including all treats? Has she laid an egg recently, if she's laying?