Thank you. Is it possible that she could have adhesions from her spay surgery.
I also feel you should give her some more time. 2 days since her surgery isn't very long, and she had some pretty serious gut reconstruction there. Her insides must be well shook-up!
Certainly you could ask the vet to include an anti-emetic drug perhaps in her IV?
I am so sorry it must be hard for you. 2days is not very long very long at all and she is only 3yro so after all this you should give it a few more days for sure.
If she is still as the vets its a pity they could not give her a tranquilizer to keep her sleeping to let her surgery heal a bit as the vomiting would not be good at all. I think it is called an induced coma.
That way she is kept still, relaxed and in no pain.... look into it anyway. I know it has a valid place in medicine for a while now talk to your vet about it.
Please keep in touch and let us know how she is going.Also it might be a good idea to consult the vets on here for a second opinion they donate their time and are very supportive.
I am sure when they wake up other members will answer you as well.I am in Australia.
sincerely Joan.