new chook dead

One of my new speckledy's has died at the first attempt to lay an egg. The egg was shell less and broke inside her. She seemed to be slower in maturing than the other two birds who have been laying for about 5 weeks. Has anyone else had this happen with new chooks?

Thanks Andy
I noticed a few weeks ago that her back end didn't look quite right but it seemed to sort itself out. I had forgotten about that.