After a day of this, I took her to a well reputed vet,
and asked for a thorough exam. Turns out, she had
parvo virus. We caught it early, and she survived (had to stay at the vet with an IV), but this can normally be fatal. Not trying to alarm you, but it's best to get a second opinion and act on it quickly- I know that certain breeds are very susceptible to parvo if they haven't had their shots, and shepherds are one of them. Make sure all the bases are covered.