Can chronic anxiety over a frightening situation cause all over muscle twitching that can last 2 weeks or more?

Not clear what you mean by "muscle twitching". Severe anxiety could could diffuse trembling or tremors. Muscle twitching might imply fasciculations or even myoclonic jerks, which are not caused by anxiety. Suggest this be handled by an exam at the office of your personal physician. Best done here via a virtual consult (www.connect@healthtap.com).