
Some bitches will be more careful with themselves almost from the get-go, other not until their increased girth makes it impossible to belt around. I've never had one be tender round her stomach (don't prod her!) or keep stretching however. I'd suggest you talk to your vet is this continues, although given she may be pregnant, going to the vet where sick dogs go, may not be a wise move. Perhaps he can examine her outside the office?
If she has a nasty discharge going on, then for sure, I'd be off to the vet. It is possible for her to have picked up an infection via the stud dog. Even if she has conceived, what's there will be tiny 'pearls' right now. So the only thing that would affect her would be hormonal.