My dog was doing the same thing. She is almost 15 years old and was diagnosed with Cushing's disease. She is now on medication (Lysodren) and her Cortisol levels have come down, but she is still pacing and drinking a lot of water. She is very tired and does this during the day and most of the night. We have to keep her awake during the day, so that hopefully, she will be able to sleep at night.
