One of our silkie bantams had layed an egg without a shell so we just her crushed egg shells mixed in with her shell and she hasn't layed one since. You also want to make sure that the eggs you have crushed for her have been crushed tiny enough so she doesn't become an egg eater.
You can give her crushed egg shells and that'll give her calcium back. I also have a chicken who lays tiny eggs on days that are rainy. So we call them stress eggs but their actual name are fairy eggs.