I have a chicken who has started laying thin shelled and no shelled eggs. It started late last fall after she finished her first moult. She has access to layer pellets, fresh water, grit, and oyster shell. She is not listless, does not cough, her comb is deep red, so don't think it's a respiratory problem. When an egg is laid that is not broken, it is jumbo size and the white is rather watery. She is a hybrid and produced a large brown egg almost daily during her first year of laying. any ideas?