Well, I can sympathise with the problems of finding a vet you can trust, although 70 miles

Not sure I would do it.
Was your dog's parents health tested if there is a problem? Puppies can strain things, but I would be concerned that there was an underlying problem that caused it in the first place, particularly with hips, but also with knees. If she's not putting any weight at all, then I would get her to the vet. If she's ok and just limping, then I would rest her for a few days.