Update on mine....I changed the nest boxes a bit and she started laying again. As an added bonus another started too. Apparently they just didn't like the boxes the way they were.
I posted a similar question and am interested in answers.
One of my 2 girls (columbian rock cross) has stopped laying. She only started about 5-6 days ago. I haven't seen an egg from her yesterday or today. She seems fine today, though, yesterday she was lethargic. She is still eating/drinking...