Chicken suddenly being picked on, what to do?

[SluceableMocha]

I posted recently about egg eating but now I have an entirely different problem - one of my Americaunas is picking on the other one a lot this morning! Their names are Parmesan and Spaghetti, for reference (my 4-year-old named them, lol) They're usually besties, I had to take them together when I got them because they apparently mope without each other (says the previous owner). But I caught them fighting this morning, and now Parmesan has harassed Spaghetti into the coop and Spaghetti is now laying down in a corner of the run portion with her head tucked way under and her tail flat on the ground, like a chicken loaf. Parmesan is with our 3rd adult chicken (Taco, the Australorpe) out scratching in the yard now. I can't get to Spaghetti but I can see she's breathing. What is happening?? Yesterday they were all fine, I even got an egg from each one of them!

 

[SluceableMocha]

And now Spaghetti came out of the coop and things seemed fine, but they started fighting again! Do I grabbed Spaghetti and brought her inside, but I can't just keep her here - I don't have anywhere to put her!

 

[SluceableMocha]

She's bleeding too.