One of my year-olds seems to have a problem . . . she sat in her nesting box for a few hours yesterday into last night, and I'm worried. She seems to be wanting to lay an egg, and lifts up while squatting once in a while (and I see no egg under her), but nothing is happening. She has been a good layer all this past summer, and even all last week. Can it happen that a chicken can get "backed up" with eggs? Is there anything that I can do?? I only have three hens and one roo. They are cooped at night, but I let them out to roam the yard most every day. They always seem to have such fun running around and scratching. So much to learn . . .