and I don't know how. was working on the car this weekend for 10-12 hours and now my left hand is kind of numb, and I have zero strength in it, and reduced dextarity. Can't figure where or how I could have injured it, I'm right handed and use the left to mostly lean against hard parts on the engine while working. What do you guys think? hit the doc ASAP or give it a few days and see if it improves?