You should see a vet now. That sounds like it might be a uterine infection (they can be deadly and mainly because the signs can be missed or overlooked or mistaken for something else until the dog is deathly ill, literally). Is she spayed? It could be something else but those signs mean she should be seen quickly regardless. I hope your baby is feeling better soon.
Yep, that sounds like Pyometra, and like the previous blogger said, you should take your dog to a veterinarian right away. She could die from it.