What causes pain in the groin area with burning pains down to the knee and painful spasm gets worse with activity?

Unusual symptoms. Intriguing to consider the sartorius syndrome named after latin for tailor, "sartor", or some such. The old sewing machines required push pedals. Repetative peddling causes overuse and stress of a long strap muscle that runs from inside of knee , through mid high, and into the groin. With rest and avoidance of the inciting mechanical activity will likely resolve..