Man, you guys do need better vets over there LOL..sounds like a possible "Open pyometria" you can clear it with antibotics but if you plan on breeding her I would do it sooner then later because if she closes her cervix and it is a pyometria it can kill her, IF it is a pyo, one of the factors about pyo, IF it is a pyo, is that there are some hormonal factors possible and can tend to run in a family line, but not all the time.
If it is a basic infection(like a psudo, or micro), if they didnt culture it and just gave you a broad spectrum antibotic it might not have been suited for the type of