I was going to post almost the same topic, so I totally understand what you are going through!
I was getting about 8-10 eggs a day and now maybe 1 or 2 only from my Bantams each day. The big girls have completely quit! 1 egg was laid on the floor when I went to lock them up the other night, one of them must have stepped on it and 3 of them were going after it, for a late night snack! I snatched it up really quick and haven't gotten another egg since. That was the only egg in a week and a half.
Only 1 chicken in the coop seems to be molting, she has feathers falling off everywhere, looks like she has exploded. But I can't figure out why the rest won't lay at least a random egg. Mine get the 16% layer crumbles mixed with Grower crumbles (due to some younger ones in the coop and the roo), plus scratch in the mornings and treats of some sort each afternoon. They also have oyster shell available at all times too.
I did move all their nesting boxes, but really, how long can they hold out just because their mad I moved them? I don't think they are eating the eggs. None of the chickens are ever in the coop when I wander in. Its driving me bonkers. I figured they would slow down in the winter, maybe only lay a couple a week. But I am getting nothing from all 9 hens that should be laying.
I guess there is nothing that can be given to encourage them to lay again/more/ever(I have some that seem to be refusing to start..26 weeks and counting)?