I have a red sex link who, some matter of months ago, stopped laying for no apparent reason. At first, I thought she was egg bound as she would go into her nest and make the noise of an impending egg. But even that stopped a long time ago. Now, my other mature hens are well into their molting phase except her, which is unusual for the time of year and the cold weather we've had here in the Pacific Northwest. She seems healthy otherwise but why would a healthy hen stop laying and not molt?