My wife has a pain in her left leg, located in the central quadriceps (always same spot, always while sleeping) since a couple of months?

She needs to be eva-: Luated by an orthopod, with workup of her thigh, hip and back regions, with a detail hx, investigations (xrays, MRI as needed), labs, to diagnose the problem. From the sound of it, i believe its from her lower back affecting her l2-3 nerves. Sometimes pain is referred from the hip joint as well. Local causes maybe a pulled muscle. Or a bony lesion. Good luck, ; happy holidays.