5 week old puppy throwing up?

Maybe he is just not ready for solid food yet. If he is growing fine I wouldn't worry too bad.

Did you get the regular 2 or 3 day after birth check up? When the pups are 2 to 3 days old they are usually taken in for a check up to detect problems. You are not giving them cows milk are you!? That is a strict 'no-no'. Get puppy formula, don't ever give a dog milk. They are lactose intolerant. By now they should be on solid foods & not be nursing off mom as much. If you don't take the whole litter & mama into see a Vet , at least take the one that is having problems.

It could be that he's eating it too fast... if the vet didn't seem worried about it.

Our dog used to throw up almost every time he ate, after several trips back and forth to the vet we figured out that he was just eating too fast. We hand fed him for a little while, then fed him in a bowl with a large ball in it... eating around the ball forced him to slow down.

okayy. My dog Use to do this after he drank water too fast. Maybe It's Because You have a puppy with bad gag reflexes so you could get him his own food dish and dont put as much water in it

This could be it:

this normally doesn't happen to big dogs or big breed puppies. It's called hypoglycemic, that is temporary diabetes. Puppies out grow it once they stop growing.