I'm sorry your pooch is not feeling well. An echocardiogram (ultradound) will show if there is flid around the heart which is CHF.
I hope this is not the case. Having a sick dog is heartbreaking. We are going through issues with our beagle as well and have not been told everything by our vet.
Keep us updated as to your girl's health. They stopped Vetoryl on our dog as well.