Most likely it's just growing pains. They can be very painful for a pup. Make sure she's on an adult food so that she grows slowly and properly; Puppy food is full of nutrients that speed up growth and that can make the pain alot worse, and can cause skeletal and joint problems later in life. The slower she grows, the easier it will be on her. Many years ago we had to put a GSD puppy down at 6 months for severe pain from the long bones in his front legs growing too fast, and he was on puppy food. I've fed adult food ever since.

I wouldn't worry about x-raying her for hip dysplasia until she is 18-24 months and done growing. Puppies can periodically suffer from dysplasia during certain growth periods when the joints are lax. I have known of dogs to be severely dysplastic as pups that grow up to be OFA Good or Excellent. Most vets are trying to make a buck, and will recommend a total hip replacement if she's found to be dysplastic at this age. However a specialist would REALLY disagree with this. Wait until 18 months and check her then if it's still bothering her. All three of her breeds are very predisposed to both hip AND elbow dysplasia, and it's likely that the dogs in her background weren't checked, so it's likely she could develop it. I'd keep my eyes on it.

Until then, I'd go to the vet and make sure there aren't any other things causing her pain (maybe a skin problem?), and ask about pain killers. When my GSD pup was having bad pains, the vet prescribed him pain killers, but you can get over the counter stuff too.

Do you have any body shots of her standing naturally?