This happened to my EE last week, don't cull her, mine was fine the next day.
I gave her olive oil and plain yogurt, mixed together. Take out the chick starter for 12 hours, and just let her go crazy with the yogurt/oil mix.
Make sure she has plenty of water, and a few times over the next 12 hours GENTLY massage her crop.
My EE got irritated and would rub the huge crop with her beak, she rubbed all the feathers off the top, but she is doing great now.
I stopped letting them eat all they wanted, instead pulled the food out, and fed them a controlled amount on a tupperwear lid 3-4 times a day.
I hope yours feels better soon!