Check them over for mites anyway. Another thing that is very common, and causes problems with laying, is worms. Either do a fecal, or worm them. In many areas, people report that TSC brand of feed is not good, old, or they've had trouble with it. Another brand that has more recently had problems in this area is Mana Pro. The owner of our feed store was having trouble with his hens laying. He did not change to a higher protein, but changed brands, and no more problems with them laying.