All of the shell-less egg pictures I can find still have a skin holding together the egg, but my chicken just popped out an egg yolk and white with nothing holding them together. This is possibly the second time this has happened over one or two days. None of the other 4 chickens has had a problem like this recently, although one lays very bumpy eggs. She currently gone back to lying in the nesting box again. The chickens are about 2 years old. Is this just a diet issue that might resolve itself or something else?