I just did a search because I could not remember what the condition was that I was thinking of.. This is what I found.
Pyometra In The Dog, A Serious Uterine Infection Requiring Surgery... ThePetCenter.com
It is very possible that your dog could have Pyometra. It is an extremely serious condition and it is important that she is seen as soon as possible. I think I would get her to an ER vet today! I hate to scare you, but I think it is better to be safe than sorry.