I'm sorry.
How old is she and does she have any other medical issues?
Are they controlled well?
An emergency spay is the best option.
Because she is having discharge, it would be an open pyometra though which is better than closed. Some vets will give hormones to make the uterus contract and expel the pus but then there is the risk of it rupturing. I'm not sure how successful antibiotics in this case but spaying is generally a way better choice if the dog can have surgery. Most cases of pyometra are considered an emergency. If the antibiotics don't work, my guess is she would be in extreme danger.
I did find this:
If the pyometra is not closed and you do not want to spay your dog (cats almost always need surgery) your pet will probably be treated with IV fluids for dehydration and receive antibiotics and a medication to expel pus from the uterus and alter the hormone levels. If this treatment does not work, or if the pyometra is closed, then surgery should be done to save the life of your pet. If the non-surgical treatment is a success 26% - 40% of females will have a recurrence of pyometra within one year.
Read more:
http://petcare.suite101.com/article....xzz0Ih4sKyRp&C