All chickens die of unknown reasons unless you get the body necropsied. But the best guess with your hen is a chronic reproductive issue that is not treatable. I lost a hen to this issue just last week after trying to treat her with calcium, an antibiotic, and miconazole for the accompanying crop issue. I even tube fed her to keep up her strength. But she died despite doing all that.
I believe the only things you haven't tried are tube feeding and an antibiotic. If you're not ready to give up, you can try those to satisfy your doubts about doing all you could.
I believe the only things you haven't tried are tube feeding and an antibiotic. If you're not ready to give up, you can try those to satisfy your doubts about doing all you could.