I had one die on a nest just the other day and I can tell you for sure that it was not egg related, but liver related. Either way, it's very easy to find out. Not trying to be insensitive, just want people to know that there are other options.
Sorry for your loss, too. I have also lost a few...
So sorry for your loss... If you're brave, you could always try to do your own necropsy. If not brave, you could send her to your state lab and have them do it.