Last Night Out Of Nowhere My Left Thigh Started To

Last night out of nowhere my left thigh started to bother me with some pain and tightness it was pretty uncomfortable when sitting i would need to move a bit because it was uncomfortable. Today it's not as bad the pain has gone down to a 2 any idea what could be causing this for the past 2 weeks I've been driving a cab for 12 hour shifts with a few breaks