I guess it all depends on the dogs health at the time it was infected. I wouldn't think that an animal with rabies will live very long though, maybe 2 or 3 weeks. Maybe your pet had parvo, a common illness unless it was pretreated for the disease.
If A Dog Gets Rabies How Long Does It Live Without Treatment?
Just a couple of weeks. If you suspect rabies get her checked ASAP and get to the DR to get shots to protect yourself.
Go to a vet asap