HELP! 10 WEEK OLD POMERANIAN THROWING UP

I purchased a 10 week old teacup pomeranian from a person who i recently found out has never got his puppies vet checked. I drove 4 hours to get him and on our way home he seemed fine. Around 4 am i heard him kind of choking a little trying to throw up and the vomit was brownish red. He's very playful, no diarrhea, his previous owner gave him canned food but i tried giving him kibble right away. He threw up again today too but it was clear foam. HE overeats a lot too but i dont think thats the cause of him throwing up. He only has 1 shot and it was the parainfluenza-parvovirus shot. I dont know if it was even done properly. PLEASE HELP THIS IS MY FIRST PUPPY I HAVE OWNED.