Goldfishes, here is an article about hens with damaged left ovaries effectively undergoing sex reverse: http://www.backyardpoultrymag.com/spontaneous-sex-reversal-hen-just-become-rooster/
In addition, if you search "hen taking on role of rooster" you'll find several discussions of hen taking...
If you do not have a rooster, often a hen will assume this role, protecting the flock and even crowing. I believe they stop laying when this happens. You describe her as loud and as a watch chicken, so it sounds like she is focused on protecting the flock.
If you do have a rooster, perhaps he...