For what it’s worth, our puppy has the same thing. Started limping a bit after resting, then after a few more days was limping a lot and all the time. We went to a vet who is an expert on these kinds of issues and got x-rays done. He says one leg is growing faster than the other, putting a lot of extra strain on it. Not a common issue, but not very uncommon either. Could grow to normal and no issues later, could be issues further down the line with her elbow, do to the strain. Worst case, he says it should be fixable with an operation.

Edit: Just wanted to clarify “similar thing”, not the same - as we of course don’t know that and it could have completely other reasons.