I'd say she is broody and that she probably isn't going to get down to eat or drink, or even poo! I have no experience with an old chicken being broody. My only one was just about a year old when she went broody and she was apparently very easy to break. I took her off the nest and out of the run for some supervised play time with a friend. I had her out for about 3 hrs in the am while I did yard work and then for another 1 1/2 hrs in the afternoon. Then once all the others had laid, I covered the nest boxes for the night. By the next morning she was over it. However, if you want her to hatch the eggs, it sounds like she would do just fine. Good luck! Oh, if you are going to let her hatch them, you still may want to bring her out for food, water, and to poo now and then.