When was she last in season? False pregnancies happen right after they go into heat, mimicking the symptoms had the dog gotten pregnant. So that would be about 2 months (give or take a week or so) after she went into heat. Most vets recommend spaying a few months after the last heat so that all the hormones etc are normal again before spaying. So she possibly was spayed too soon after the last heat. It may be uncomfortable for her right now, but she'll make it through. I just don't know much that they can do for her.