Definitely have a very thorough vet check asap, make sure vet knows your concerns about breeder. But if it were me I'd sign up immediately with pet insurance. Each company is very specific and pre-existing conditions will be a problem, going to a pup ER you will probably have to pay up front but that insurance can really help out! You can always cancel insurance, should you decide not to keep the pup. Tho that would be a difficult decision knowing what you evidently know about the breeder. Good luck and I hope your baby is healthy