One hatching, umbilical attached to eggshell?

[Coops Dad]

One of the eggs in the incubator just unzipped and the chick emerged 15 minutes ago. She still has her umbilical cord attached to the shell; there's no bleeding but she is noisier than any of the prior chicks that we've hatched. She's vigorous and seems to have gotten her legs under her very quickly. Should I have any worries or just keep an eye on her and make sure she doesn't pull the cord off before the blood vessels seal off and it dries more?
Second issue- this egg stunk bad, not sulfurous like a rotten egg, but like a high protein fart. What is going on with that? Every other hatch was much less vivid, odor-wise.

 

[Coops Dad]

I figured it out. The umbilical cord detached from the chick, leaving a little tag on her belly and a longer, bloodless piece attached to the egg. And the stink was coming from another egg with a dead chick inside. The embryo looked to be about the size of a whole pecan nut and the mess stunk like the devil's outhouse when I dropped it into the burn barrel.