I am sorry..yes it does happen when parents have hip and elbow clearances but it much much less likely and you pulled the short straw. I did that with one of my dogs. The whole litter had problems but both parents were very good and there was no real indication in the lines to predict the outcome. The inheritance of bad hips (not sure about elbows) is genetically very complex.
Get her x-rayed. Talk to the breeder. See if she will give you a refund instead of a replacement puppy or a half refund or whatever (She is only bound by the contract, though). Most will let you keep the ill puppy and get a new one but a second puppy is the last thing you want when you are dealing with this.
Well I know you are having a tough time with it and hope the veterinary folks come up with good resolution or that it is not as bad as it looks. You will find others here who have been there