Can you take some photos in natural lighting (without the red light)? Thanks!
Hard to tell, could be prolapsed, can't really tell. I would keep the vent cleaned (gently) and apply a little coconut oil or anti-inflammatory cream to the vent.
See that your chick is drinking well. If she's pushing hard or constipated, give her a bit of coconut oil to eat - it can be given as small chunks or mixed with a little wet chick starter.
Poor baby!
That doesn't look very good, is she able to poop o.k.? eating/drinking and active?
I would keep the vent cleaned, but also keep it moist with coconut or anti-inflammatory cream, you don't want the tissue to dry out. She may need to be placed behind a barrier to keep other chicks from picking at it, it looks like it's becoming raw.
She's eating, drinking, and active. I wiped it with a cotton ball soaked in warm water and put Preparation H on it. I have two brooders going. I might put her in the one with less chicks.