There is also a possibility of sciatica, although usually this is accompanied by discomfort in the cheek of one side of the behind. The second step would be an MRI of the lumbar region L1-L5. So basically, there are two "rule-outs", "sciatica" and "intermittant claudication" (essentially partially blocked blood vessels) and only after an in-person evaluation by a physician can there be a true differential diagnosis.
This is characteristic of a vascular issue, probably intermittant claudication, and generally the next step in diagnosis is a color doppler image of both legs. It's a yellow flag and you should see a physician for an evaluation in the near future.