My RLS is an uncontrollable - almost vibration-like - sensation under under kneecaps. My legs don't twitch and they aren't sore. But the desire or need to move them is overwhelming.
From
WikiPedia:
Restless legs syndrome (RLS) or Wittmaack–Ekbom syndrome is characterized by an irresistible urge to move one's body to stop uncomfortable or odd sensations. It most commonly affects the legs, but can affect the arms, torso, and even phantom limbs. Moving the affected body part modulates the sensations, providing temporary relief.
RLS causes a sensation most closely compared to a burning, itching, or tickling in the muscles.