
Poor girl, she must be feeling really miserable :( The bestthing to do for her is keep her busy - take her about with you, take her for lots of walks, etc. Don't give her time to sit and mope and feel sorry for herself and she'll get over it a lot quicker. And try not to let her get attached to toys as "surrogate pups". They take a lot longer to recover if this happens.
I'm told all bitches have phantoms to a greater or lesser extent after seasons (especially wild dog packs where the unmated bitches will act as nannies to the other pups), but when they have full-blown ones like this they tend to have them badly every time, and in that case spaying will be the only sure cure :(
Hope she recovers soon.