Man, oh, man, I would be getting a second or third opinion. Lethargic and abnormal poops!?!?! You have to keep pushing for them sometimes when you current vet is not working out for you. You have to find out what is going on with this baby whatever it takes. It may just be from his medication but frankly, you can't afford to assume that and have to find out what's really going on and if he's lethargic from weakness from losing fluid or he could be in pain. Dogs often hide anything but sudden or acute pain. Time could be against you. Please read these links to see if you can find some guidance:
http://www.yorkietalk.com/forums/eme...-drinking.html http://www.yorkietalk.com/forums/eme...-articles.html http://www.yorkietalk.com/forums/eme...-dog-pain.html