@MadThom , I think you are right to be concerned something is really wrong with your chick. In that group photo you posted, it is clearly lagging behind the growth rate of the other chicks.
Prolapse usually refers to the vent, while a hernia would address the abdominal area.
Since you haven't...
It's also hard for me to tell for sure on my phone screen, but it looks like the chick's navel didn't properly close. If so, it is an open wound and susceptible to infection. I've never had a chick with this condition, and don't know how to advise.