It does look like they're molting. It normally starts at the neck. Laying is usually affected by molt. You treated with sevin dust, make sure you do the follow up too. I would put a little at the bottom of the nest boxes too, then put nesting material on top. Make sure you have free choice oyster shell available for them. I would make sure they have shade too. The skin can get sunburned during molt. I had one that was so bad, I put a little sunscreen on her. Get a bag of showbird feed, and mix it in with their regular feed, or spread it around generously as a treat for them. I have found that supplementing their diet with showbird feed does wonders with feathering, and egg production during molt. I wouldn't feed them the showbird feed exclusively though. When the new feathers start coming in, try not to handle them much. Did she have a rooster?