Hello, I have this issue that's been bugging me for three years now.
I've seen several doctors, tried physical therapy--hoping someone here may have more insight.
Several years ago, I probably injured my foot somewhere by running (new to it). Initially the pain was limited to my left foot (bottom of foot + ankle) where I'd limp for a few weeks. It would be painful to stand on that one feet for a long period of time.
Eventually the pain did go away. However, I would experience weird symptoms. When sitting down in the car driving for an hour, my left leg would feel numb. I would get twitchy spasms on the upper-left body from neck, to arms, hands, fingers, sometimes even face. Did MRI scans on neck, torso, docs didn't see anything weird. The numbness issue did eventually go away on its own after 6 months or so. I started wearing foot-arch inserts which I think helped a bit. If I walk too long without them know, my left foot + calf would feel really tight.
Occasionally, I still get some twitching on the left side when I sit in the upper body.
Doctors first guess is sciatica, piriformis syndrome--but they can't link that to the upper-body issues so I'm puzzled.