Shi tzu pup not eating

Question
I'm new at the "puppy thing" so some help it really appreciated right now. I got a pup a week ago, he is just 7 weeks old today. He did fine with eating and seems to adjust to his new surroundings well...until today. He hasn't eaten a thing all day, I even tried to warm some milk for him and he wanted nothing to do with it. He doesn't even want water, I've been moistening his mouth all day just to keep him hydrated. When should I start to worry about this? He does chew on the grass when he goes out. Do you think the grass is making him sick? Help!! Thank you!!

Answer
It sounds like he just has an upset tummy.  Dogs eat grass to aid digestion or to make themselves sick if they aren't feeling good.  He will be fine.  Of course if the not eating persists for more than 24 hours,  or if he's not drinking water then take him to the vet.  Oh and don't give him milk.  It isn't good for their stools.  Will make them runny.  Some dogs are also lactose intolerant.