Weigh her soon, I am sure you have checked and re-checked temps and such and that nothing major has changed (has it?) I'd assume that is is just that time of the year I have 2 adult females and 2 adult males off food at the moment.

The best check of the health during a fast is weight. For example my big female was 3544gm in january and has been fasting since then she was yesterday 3477 that is 67 gm loss nothing really she goes up and down a bit as well. Check the weight and weigh every 2 weeks or more (every week is what I do) and you keep an eye out for serious weigh loss.
Alex