
Get the pup to the vet straight away. Take no chances with a puppy.
How old is the pup, and what breed? If you are giving it milk I assume you are the breeder and have the rest of the litter. How are they, and is mum all right? If it is old enough to have left its mother (about 7 weeks old) then there is no need to feed it milk. Instead it should be on a good quality puppy food.