One of our chickens has not laid now for almost 3 months during the months of June and July and some of August. Over the last day or so her comb is very pale. She is a light sussex and always her comb is a good indicator if she is not well. She is 3 and half years old. Been a good egg layer up to now. We have wormed her and checked her for pests and medicated accordingly and are confident it is not a pest problem. Not sure what the problem could be and why she is not laying. Does anyone have any ideas? Thanks.