Yolk or hernia? Please help.

[Millieshens]

I’ve just had our final chick hatch out, (end of day 21, no assistance. Egg was cheeping all day yesterday day 20 and externally pipped some time overnight.)
The poor thing has something hanging off it, I presumed yolk sac to start with but I think it might be coming more out of the back? I don’t want to disturb her to check, I just whipped out the other chick so she’s be on her own and put the incubator into a dark cupboard for her to rest.
Should I do anything else? Is it yolk?

 

[The_crazy_chicken_girl]

Yeah, I think that’s yolk sac one of mine hatched with the same problem

 

[Millieshens]

I’ve just her her out. She’s lively apart from this. It’s definitely coming from the skin on her back. Navel is closed. So strange.

 

[Millieshens]

Ok it’s not coming from her navel or bottom. What is it? Anyone know? Do I need a vet?