She might have torsion, where the stomach turns over on itself. Please get her to a vet right away. Like right this afternoon.
She could have eaten a toy...intestines anything get the baby 2 a vet!!
My dog had her stomach turn upside down and her bladder and sex organs switch place she was a sick baby, we took her 2 get spayed and they fixed it all for free!!
For "free" or do you mean you paid only the regular cost of spaying? I suppose if they have the dog sufficiently open to simply mover the organs around then why not "free" for that part. Still I bet most vet would add a couple $100 at least for the extra work.
Please get your puppy to her Vet ASAP....From what you describe, she's in serious trouble! Please, do not wait any longer looking for answers on the internet.....She needs a doctor (There are None here), now......Karla