When I stand up my body contorts for a few seconds?

Ever since I was about 12 when I stand up my body contorts for a few seconds. It only happens when I stand up and start walking. Or if I’m standing still and then move suddenly. When its at it’s worst, I stand up and walk then the left side of my body kind of… contorts. It starts at my foot. My toes will curl then my ankle bends inward. My hip juts out and then my wrist curls inward and my fingers spread apart and they curl. Then my left cheek will tighten as if I am snarling and my eye will twitch. It only lasts for about 10 seconds but it is very embarrassing in public. I have learned that if I stand up and then stay in place for a few seconds it wont happen. I can feel it “flaring up” and then it passes. If it goes to the full contortion and I try to walk it off it’s worse and my arm will kind of flap around. And if I try to speak my speech is slurred. can barely hide it from people in public when it does I have to bend over and pretend im tying my shoe so they wont see my arms and face spasm. i have no idea what problem could be any help will be appreciated.