How old is she?
so of the cuff here.,
first my pet peeve. I'm convinced through a year of research and experience that sorghum changes hormones. Check your feed. If it has sorghum, toss it out and get a grain or corn based feed. There a huge post by me and others here on BYC in this...
My two hens that underwent "gender transition" eventually went back to being laid after i put a rooster in there, and eggbinding would've been my first guess but you eliminated that.
Hens also squat to poop and is the same vent, so anything "plugging her" would've been noticed as well.
I'm...