I have a sensation of desperation on my left arm and left leg, punching it brings seconds of relief. In a weird way, pain helps me for a very short time. It s at night or when I m standing still when it hits me the worst. In fact some days I felt like cutting off my arm. For years I thought maybe I was crazy until my sisters told me they have the same problem.And now my younger daughter has it on her left leg but from experience, I know that it moves from limb to limb. My uneducated guess is my nerves and its hereditary.