Every so often, I get these pains in my leg or arm and sometimes just in a finger. It happens at random and I'm not sure what triggers it. The sensation is sort of a deep throb within my limb. It almost feels as if it could be bone deep. It is very unpleasant and sometimes keeps me from falling asleep. When it happens I usually try to ignore it and it ends up being gone by the next day. The pain seems to center around my elbow or knee. What could this be?