If it's little chicken's navel, it could possibly shrivel up and fall off. That is being optimistic. I have read of infections of the navel too. Again, though, I have never experienced this personally. I hope someone responds to help soon. Poor baby.
If it's coming from her vent it could be more fatal.
Is it coming from the vent and look like it could be it's intestines? Could be hernia or it could be prolasped.
If no one responds soon, I would contact a vet to see if they could point you in the right direction.
Is she eating and drinking okay?