I have a small flock of laying hens no rooster. I have noticed over the last two days that one of my hens Rocky (daughters named her) has been waiting to lay her egg till there are at least three eggs in the nesting box. Then she stays put for hours lets out this weird high pitch almost scream when the other hens try to get near her. She also wont let me close and tries to peck me whenever I reach my hand in to grab the eggs. I have to put down dry mealworms for everyone just to get her out. She is one of my most calm chickens even likes to sit on my shoulder. I have never has any problems with her. Why is she being so odd and aggressive now?