I certainly hope you take action and read up on what you can do. California is much more progressive when it comes to protecting the person who purchased the dogs then many states....There is a lot of information out on the internet to review...just plug in California Puppy Lemon Laws...
Dog-Play: Getting a Dog Tips - California's Puppy Lemon Law California Puppy Lemon Law
Take your emotion away and follow the law. You now need to do your homework even though you didn't when you bought this dog. Hopefully your little one will recover.