I'm sorry t hear about your dog.
Quite a few things can cause a nose bleed and the foaming/drooling may have been associated with pain, discomfort, nausea or nervousness.
If it has stopped, you just want to keep checking daily for any return or changes in behavior/ routine/ attitude.
Eventually, you also may want to have a coagulation profile run on your dog, to make sure no clotting deficiencies exist.
I've found you an article to read about nose bleedings in dogs, so you can consider options if you feel your dog did not have a sneezing fit causing irritation or inhaled something irritating or injured her muzzle just before this occured. There are quite a few things which can cause this, including but not limited to: XXXXX XXXXX diseases, heartworm, lepto, trauma, foreign bodies (sometimes not seen with x-ray but endoscope can find), hypertension, neoplasias, and of course sinusitis.
You can apply cold compresses to the muzzle if bleeding starts again, but if the bleeding becomes moderate to severe, this becomes an emergency. There are medications your vet can use directly in the nose to help stop the bleeding.
Best of luck to you, and please let me know if I can help you further.