She needs to see her vet today, asap. That could be a variety of things. It could be something like a uterine infection or something like a tumor or a problem with her organs. Bloating is likely being caused by something inside. Either some type of fluid or an actual growth or maybe even a severe parasite infection and it is making her very ill. Or was this more sudden? Could it be actual bloat (in which case her belly is filling with air and her stomach is likely to twist) and she was trying to retch? That can be deadly within hours if she doesn't see a vet and is very painful. I'm sorry she's not feeling well and I hope things turn out okay for your baby.