4 month old puppy Nico has been having diarrhea I tested his fecal and he is negqtitive for giardia , he drinks and eats well and his energy is good. I’ve changed his food I was doing blue buffalo and now it’s orijen puppy food but I’ve noticed his stools getting darker and darker and today his stool black black like tar looking and watery/mushy and im not sure if I should just wait a few days and let it pass by ? I have done metromidozole and clava