Poop won't pass until the egg does. It's blocking off her anus that's on the right side of the oviduct(Vagina). Chickens have a two "valve" system set up that's divided, but connected.
Molasses is good for treating constipation, but not egg binding.
She's gonna need extra calcium to help with her contractions to push the egg, out. Calcium Citrate Tablets work great if you got any.