No we did have an issue with moldy feed right before all of this started. My bin was leaking at the seam. We quit using it once we discovered mold, but it doesn't appear overnight, right? Maybe it's connected and maybe it's not, but I would never have put those two together on my own. I was worried about and looking for physical illness, but not behavior changes. I feel like a dumb now. Thanks for that info; I will not be a dumb in future.
We do not have a rooster. This is my first flock, and I didn't feel confident enough to get a rooster with the hens. Or to get straight run.
I didn't think of a banty; I'll keep that in mind. Apart from the lack of confidence, we do live in a neighborhood, and I don't want to cause the neighbors undue annoyance.
The runty one does lay and seems fine other than this issue with the other hen, but I may still try separating the lowest two and see what happens. However, my daughter just saw our "bully/roo" pin another bird and maybe pluck feathers, but at least peck the neck, then let her up. But I think if she was truly wanting to pull/eat feathers, probably more birds would be more bare by now? She's been back in with the flock for at least 10 days.
I truly appreciate the replies. Probably the wisest route would have been to "apprentice" with a flock owner and then set up for my own flock, but that's just not at all how I did this! Thank you for helping me figure this out as I go.