Those oats should be in a bowl, or at least scattered away from where they poop. It appears that you have oats scattered right under the roosting bar. There should be some kind of bedding under there that you should clean regularly and keep the food away from there.
I would treat the whole flock for coccidiosis in the meantime.
I’m not sure what a chicken misscarige is, doubt it was though, that’s what my dad thinks but he doesn’t know much about chickens
She was rubbing the chicken comb, thank goodness it didn’t get pulled off!
It looks like someone got pecked. That can happen from time to time from a tussle over food or a pecking order thing. Just have a look at your chickens for any bleeding combs, wattles, or a blod feather. Many times you cannot find the source. Look for more blood later, especially if it is in droppings.
I agree it is likely a pecked comb issue. Keep an eye on poop, just in case, but I wouldn’t worry too much about it at the time. Do any of them have feathered feet? My Brahma broke a foot feather once snd there was a LOT of blood.