Please excuse all the typos in my post!!
Poor little thing! I agree absolutely with Tony (above)
The food was probably either too much at once, or maybe a bit rich for him at his age. He might have guzzled too. It's likely he just had a very bad tummy upset.
But with a very young pup, that can sometimes become dangerous as pups can dehydrate very fast if they vomit or have diarrhea.
Make sure he gets Pedialyte (unflavoured) If you can't get that then small amounts of water. Don't let him rink too much at once but get the fluids in hm little by little and keep a good watch -make sure he keeps it down.
Obviously if ou are worried AT ALL about him, get him immediately to a vet, or even an emergency vet, if he vomits the fluids back.
Then when he is recovered, make sure he gets puppy food, and that might be small portions, five or six times a day or so for a little while.
I also think seven weeks is a little young to be taken from the mother and littermates. I always think OVER eight weeks -maybe even nine or so, is the best age. Even those extra 2 weeks can mean a lot, as they are still learning doggy social skills very quickly at that age, which are best learned with mother and siblings.
Hi. It's doubtful it was the food content, although 7 weeks is very very young and normally at that age they have only just finished being weaned from the mother. I personally think this age was too young for a pup to have been removed from its mother. The puppy should also be given small amounts of puppy food (not adult food) regularly and in accordance with the breed and manufacturer's recommendations. It sounds like your puppy has eaten too much too quickly, or has eaten something else that has upset his gastric system.
I note the post was some days ago - so has he improved since then?
Tony