I have three 14 month old golden comets. They've all been consistently laying since last August, even through the winter. About two weeks ago I started noticing one egg out of the daily three had a rough, dark spot on the very bottom of the egg about the size of a nickel. Some days it was only rough but a few times it was a very soft shell in that area that broke easily (including once in the nest). Now it seems that which ever hen was laying those eggs has ceased producing all together. I don't know which one it is, yet. I'm still fairly new to raising chicken though and want to make sure that I shouldn't be worried a bit more, especially about disease affecting all three. Any help from more experienced chicken keeps would be very welcomed. Thanks!