Yes, you need to get her to a Vet ESP since she just had a litter. Did she deliver at home or did the Vet assist? Was she up to date on shots? Have the puppies had shots? I assume they are weaned.
Please update.
Take her to the vet ASAP.... I don't really know what it could be but if my dog goes without eating for a day I worry non the less two days and throwing up? Yea vet ASAP...