yeah you should always have a vet check up when you get them - do you have nutrical is that the same as what you have -also pedialyte unflavored is good to have as well. Can you try mixing the food with a little baked chicken maybe that will entice him more - some others say on here little cesars even though not a great food no dog refuses it so maybe mix a little of that in there if not chicken as you need to get him to eat as he is very tiny
also 2 mos is way too young to let a tiny pup like that go
i believe it is 12 weeks or more for a tiny like that so not sure this breeder is very good letting a tiny go at that age