What’s wrong with my cream legbar?

[Jmash]

This is how the eggs look from my cream legbar. She was laying well, but it dropped off and all of her eggs have looked like this.

What is this and how do I treat?

 

[Yardmom]

What is her diet like?

 

[Jmash]

I feed her the same as the rest of the flock. They get Bar Ale organic pellet feed. I offer oyster shells and they get fresh water daily. They also have a large free range enclosure, so I don’t know what else she may have foraged.