How are her back paws? is there any abnormal wear patterns on them? There are several things that could be causing that shuffling, from arthritis to Degenerative Mylopathy(which shows up some in Shepherds in particular), all of which the vet can look for. But they should also do blood tests to rule out any imbalances in her endocrine system, which can sometimes result in mental changes. I hope the appointment is soon, and you can begin to get some answers, it could be several unrelated things, on all one issue.

Any changes in the family or new animals or anything?