So i got my new guinea pig two days ago and today i noticed that his poop went from brown to green. But i gave him spinach yesterday. He has unlimited water, food and Hay. I read about the yogurt treats and how they are lactose intolerant and i am wondering if thats what is making him sick. He is acting normal and running around. But his poop is worrying me. I am a new mother to a guinea pig. Help!