Some chickens will stop laying in winter, it's not uncommon for no eggs to be laid for up to 2-3 months, we have bred chickens to have an unnatural ability to lay eggs constantly, some just don't always comply, they stopped because they don't have the ability or the right conditions to lay, they are living creature that are subject to stress and the need to rest, image how it would be to give birth a few times a week, give them time, wean them off the light which can mess up laying and make sure they are getting enough protein.