What Causes Numbness In Hands?

hi doctor, i have this numb feeling in my left hand which started yesterday. Before that I have this pain in my lower left side of my neck which I got maybe from working out in the gym few days ago. I also have numbness in both hands when driving on my way to work in the morning. I never had this feeling for 2 days straight now, I am am quite worried about this numbness. Maybe you could shed light on my situation. LOUIE