Is my baby chick injured, or just sore?

[ChickenFan73]

We are not super new to chicken raising, but we have never had this problem: one of our baby chicks keep ripping out its tail down/ feathers and peeping loudly. It is also not letting any other baby chicks near it.
More to the story:
We have a bunch of day-olds and a few of them had pasty butt. We took care of that, but now one of them keeps picking out their down and the area around the vent has NO feathers and seems red and swollen. It keeps picking at the area around the vent and when it isn't doing that, it is just making the loudest peeps I have ever heard. It seems in distress, but we don't know what to do! The skin looks all iritated and sore now. Any help would be appreciated!
More details:
no blood, at least not yet.
Heat lamp is strong, and the temperature near the bedding is a cozy 97F.
Haven't seen the other chickens pick at the vent when they get a chance - but that isn't often.

 

[micstrachan]

Poor sweet thing. Can you post a video? I wonder if she is backed up, uncomfortable and trying to deal with it. Can you give her a warm Epson salt bath?

 

[micstrachan]

Also forgot to ask, can they get away from the heat lamp if they want to?

 

[ChickenFan73]

Yes, they all can. There is water in both the warm and cool end of the enclosure. It's only one of the pasty butt ones