What to Do If Your Female Dog Has Pyometra (Uterine Infection) - Associated Content
It seems far better to spay instead of hoping that antibiotics fix the problem only for it to possibly return.
There is no way I can say if this is what she has.
Is the discharge very red or is it more like pus?
Blood work could be done but I think x-ray is a good thing to do.
Maybe it is just a split heat but why is she wobbly then?
Is her belly swollen?
If you are questioning your vet, can you go (today) and get a second opinion.
If they agree with the first vet's advice, then stick with it but now she is throwing up the meds, so something has to be done anyway.