I am sorry but this man you bought the puppy from doesn't seem to be a responsible breeder.
If he truly cared about his dogs he would be just as concerned as you about the puppy's health and not so concerned about losing money. I am sorry your family has to go through this but I agree with others that you should return the puppy before your child gets further attached and possibly heartbroken further down the line if the puppy becomes ill. Best of luck to you!!