I constantly have this terrible numb/stinging feeling in my lower legs, feet and hands. It is also accompanied with sharp lightening like pains every few minutes or so. It keeps me up with little to no sleep for several days at a time. The only time I can get any type of sleep is if I take over counter meds with sleep aid & that only gives me about 2 or 3 hours at a time. What could be the cause of this?