They can lay dud eggs even if they have not been bred. She may be ovulating and searching for a mate. If she is a healthy adult, she can go months with out eating and be OK. The best thing to do is to just keep trying to feed her every so often and wait until the season runs its course. If she doesn't eat within about two months, you may want to get a little concerned, but as long as she looks good don't worry about it. Good Luck!