
I,d be popping him to the vets before you do any starving he,s only a little mite yet.
He should be insured at least with the kennel club for the first six weeks and if you only got him new years eve this may still be just a bit of stress with his new home ,change of diet etc.
The dogs he,s playing with are they your own? I,d be very careful of letting him play with dogs outside your own property until he,s had all of his puppy jabs.
Hope he,s soon feeling better
Sharon