Does anyone know what's wrong wiith my puppy that isnt pooping?

i took my pug puppy of 8 weeks Iggy, to the ER last night. he has hardly been pooping and when he does, it's terrible diarahea. They gave me some medicine for the problem. I don't know if the diarahea stopped or not because he hasn't pooped or peed all day long! He doesn't even feel like drinking water. I've been giving him hamburg and rice and the vet said it was good that I was doing that for him. Is this normal? My puppy needs to poop!