Good for you to have discovered her plight! You can use cortisone cream on the vent if it's swollen. Apply after the Blu-kote dries.
It might help to make some chick toys for diversion away from chick butts. This might give you some ideas.
https://www.backyardchickens.com/articles/aggressive-baby-chicks-and-how-to-stop-the-behavior.72029/ It also explains how to discipline a baby chick to stop bad behavior.
I've taken a tennis ball and drawn red dots on it with red magic marker and made a little pecking toy from a window foam insulation noodle stapled to a block of wood. I wrap red duct tape around the noodle to draw their attention. I also stuck red duct tape pieces on their heating pad and you can see the chick on the far right pecking at it.
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