My Araucana hasn't laid an egg in about 3 weeks. HELP!

We started a small backyard chicken hobby in our backyard in our subdivision. We have 3 ISA Browns (great egg layers), 1 Araucana and 1 Bantam.

All are about 22 weeks old. Our ISA Browns give us 1 egg every day (never missed a day since they started about 2 months ago. Our Araucana has given us about 10 eggs and was doing it pretty much every day when she began, but for about the last 3 weeks she hasn't given even 1 egg!!!! She seems healthy, she's tame and let's us hold her. She eats well (just as much as all the rest), so I think she's fine but I don't understand why she just stopped giving eggs cold-turkey a couple weeks ago.

I switched their feed a couple weeks ago from "grower/finisher" (15% protein) to "layer" (16% protein) and they would have been about 18 weeks old. I also feed them "treats" from time to time of corn on the cob, watermelon, cucumbers, crackers, breads, mealworms, etc.

All of the chickens are in an enclosed run/coop. No other animals can get in (1/4" hardware cloth all around). No signs of her eating her eggs. She ALWAYS used the egg boxes. I've looked everywhere to see if she's hiding them (none found).

Any idea why she would just stop laying???? What can I do? I know they only lay about 180 to 200 eggs per year, but how can she just stop all of a sudden?

HELP!

Thank you!

 

Finally............... She gave us an egg today (9/7/13)!!!!!!!!!!!

I was thinking yesterday that when I gave them all a couple slices of bread each day was when I was getting 4 eggs (from the 5 chickens) per day. So I gave them bread yesterday and I got the egg today. I wonder if this could be the reason????