I am no expert, but I thought that they usually only spay 3 months after a season and I'm suprised the vet has carried on on top of a phantom as her hormones must be all over the place, never mind the operation.
I would ring the vet for advice as she shouldn't be so upset/crying now. You could try some arnica to help with any bruising and there are many homeopathic remedies that could help soothe her but I think you need to be sure she doesn't have an infection or something wrong.
Hopefully someone with more experience will be along soon