I have 5 hens, the reds are 29 weeks, barreds are 30 weeks and we aren't sure of the black hen, she was given to us. She was already laying when we received her a month ago and since has been very consistent. 2 days on 1 day off. Until this weekend. She hasn't laid in four days. None of the others have started laying either. She last laid a nice large egg last Thursday. We found a very tiny darker brown egg on Friday which we thought may have been the first egg of one of the other girls. Nothing from anyone since. They have all been on laying feed since 19-20 weeks old. Any help??