False Pregnancy?

I have a 9 month old female jrt. She was just spayed last week. When I picked her up the following day, I noticed that stomach seemed very swollen so I brought her back to the vet the following day. The vet told me that she was experiencing a false pregnancy. I wasn't able to ask him too many questions because he was called into an emergency surgery, but he assured me that she'd be alright before he left. So, my question(s)...has anyone on this forum dealt with thier dog going through a false pregnancy? Is it common for a first heat? How long will she be like this (nesting, hiding, cranky towards my other jack)? Is there anything I can't do to help her? Any information you could provide would be greatly appreciated.

Thank you,
Nicole (and Gracie)