I Was Involved In A Car Accident A Year Ago,

I was involved in a car accident a year ago, And i've noticed over time that when i stand straight and bend my knees at all my legs quiver and shake horribly bad. I have no control over them when they shake and i cant stop them from shaking. Its limiting my ability to lift things from the ground badly. I really dont want to go to any more doctors at the hospital im sick of it... Can this just be like.. Normal for someone whos 21? Weak muscle or something?