My 9 week old puppy has a hernia?

Hi i have a bernese mountain dog and when we bought him he has a umbilical hernia, he had it checked by the breeders vet and he said it was fine then when i bought him my vet checked him out and said keep an eye on it, but is shoulf br alright, but now it seems to be getting bigger, what could be happening here he is going back to the vet on monday but is there any opninons on whats happening