I had a pain just like that five years ago, and it was Shingles. Probably not the case with you, but it was the exact pathway. It took two weeks to dx even though I was unable to walk on that leg when I went to the ER. The ER doctor thought I could walk if I tried. I tried, and fell into his arms. But a smarter doctor recognized it two weeks later in the same ER. I wonder why it was hard to see? All the first ER doc could see was a "hot red leg" but it didn't ring a bell--didn't I have a rash? I probably would have missed the rash if I'd been trying to look on the back of my leg.
Yesterday I had the same pain and I thought it might be a recurrence. I have a fever and cold, so I just lay there and didn't try to go to the doctor. Today, however, it is not anywhere near as bad so I guess it's not Shingles, unless Shingles comes back in a more minor way.