UPDATE: Not a happy one, unfortunately! Its been about two weeks since Luna had a shell-less egg break inside her. Her crop is still not emptying and is about the size of an orange. I have given her mineral oil daily but this did nothing to resolve the crop issue, which I believe is secondary to a reproductive issue. Sadly, she will need to be put down at this point, because she is not responding to any of our efforts to save her, and because I do not want her to continue suffering. I wish I knew what caused this issue, esp since she is only just over a year old, but we tried our best and greatly appreciate the support and advice from everyone on here!