There could be a few causes for this. The most common cause is vestibular disease. This might even cause stroke-like symptoms (staggering, one sided weakness, drooling). If this is the case, there is often an underlying cause like an ear infection.
If she is not eating well, you could also be seeing the effects of hypoglycemia. If you suspect this, you can use a little karo syrup on her tongue and see if it helps.
This breed is also prone to seizures. If you have not ruled out seizure activity, you need to see the vet to do so.
Let me know if you still have questions or if you want to discuss this more.