For the diarrhea, Rocco got an antiobiotic and a GI protectant. Also, he'll be getting some high-fiber soft dog food. The doctor thinks this is most likely caused by the prednisone, so we are going down to one pill a day over the weekend. As for the breathing issues, this is apparently caused by prednisone as well and should go away as the dosage is lowered.
But the great news is that Rocco wanted to play tug today! This is something he hasn't done since Sunday. Around 5 o'clock, he went over to his 'toy box' and looked up at it, which is his signal that he wants to play with his rope toy. We tugged for 10 minutes or so, but it was just so joyful to see him have the desire to play. We figure that he's probably been having an upset stomach for some time, and the medicine is helping already.