Thank you for the notes, it is a terrible way for them to go/if they do, and seeing anyone or animal suffer is just difficult.
But, after reading the successive messages, along with thinking back to how our hen may have ended up with the enlarged/red bum, I believe it could have occurred because she may have been the chicken who left us the MOST GIGANTIC EGG EVER! While we marveled at its size when we first collected it, and left it in the box for much longer than we typically leave any in the cartons(especially when it is so GIGANTIC that the box/lid won't even come close to closing!...keep in mind, the leghorns we have are not giants! Well, I cannot imagine that this didn't cause her the original damage, in retrospect.
IF this was the case, I don't know that there is a solution to this problem. However, this too, is just a guess. We have, or shall I say had, 8 leghorns laying and don't know who lays which one as they are all leghorns. We do have 2 bantams as well, but it is clear which eggs are theirs! We also have a rooster, a leghorn as well, but he doesn't seem to be the problem at least near as we can tell. The other hens all seem fine for now.
The lost one did not have an egg stuck, as she did lay an egg the day before we lost her. It had a totally soft shell, which is the first we had seen this for many many months.
Thank you for the notes, and hoping between all of us can figure something out at some point.