Sat with legs crossed at knee.suffering pain on outside of knee..sometimes no pain , sometime pain on swinging leg to walk..goes down calf 68 yrs old?

Pain behind the knee: Can be a sign of a clot in the leg. Sitting for a long period time in an awkward position, especially with the knee bent would be a risk factor. If the leg is swelling, discolored or the pain is increasing then evaluation is recommended.

Lateral knee & leg: Consider compression on peroneal nerve, may cause footdrop symptoms.