It's been a day and half since he's gotten back on his medicine. And he is doing so much better! We had to help him up and down stairs before and he wasn't showing much interest in anything.
Now he's barky when one of us isn't home. And he is following us around instead of staying in one spot. The spark in his eyes has returned. I didn't have the heart to tell him to be quiet while my husband's been out. I've been so happy to hear his voice.