well maybe she has a very upset tummy.... anything she could have ate that would cause blockage??
If not, try fasting her for a day and then for 2 to 3 days feed her boiled chicken and rice... plain diet that will soothe her tummy. If she STILL does not eat her real food.... then go with the assumption she is testing you and try the take away her food. do this for up to 3 days, unless she starts being normal again. If she is still acting normal but not eating, do this still. If she starts moping and being lethargic, take her to the vet as it is more then adolecence