Peeps layed 7 eggs and one that had to be removed surgically. She was not getting enough calcium either. So, upon taking her to the vet he recommended ground Oyster shells. You can find them in pet stores. I put it in a small dish and sprinkled some oat groats on the top and lightly mix them in. It makes them try to get the seeds and it gets the powder in their mouth (good thing). Now mine think of it as a treat cup and investigate it every morning.
Here is a link to another supplement that you can use:http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=6166
Also, I have a mineral block (it is shaped like grapes) in there as well. She knaws on it as needed. These things helped her a bunch she was able to pass all of the eggs after that.