Lethargic chick, smelly poop

[iam4hymn]

I just got 6 chicks from TS yesterday. I have raised lots of chicks, but we typically hatch our own or order from hatcheries. 5 of the chicks are doing well and are lively, but one is small, lethargic and has a terrible smelling bottom. I wiped off a bit of pasty butt from it, but I have never noticed a chick to smell this way before .Any ideas? (Edited to add: we have 7 eggs in the incubator that are due to hatch in 2 days. I was going to mix the babies, but now I am worried .)

 

[Wyorp Rock]

Is there any swelling of the bottom? Can you tell if the smell is coming from the vent and if the navel is closed/healed up?
Any more pasty butt?
Photos of the poop?
Is she willing to eat/drink?

I know - more questions than answers. I do wonder if your little one has an infection of the navel/yolk sac infection.

Let us know how she's doing.