Hello @howshu and welcome to Mayo Clinic Connect. You'll see that I moved your post to a discussion already talking about full body electrical shocks. This is so you can connect with other people who are going through similar issues as you.
You might be interested in this article as well What is Lhermitte's sign?: https://www.medicalnewstoday.com/articles/323889.php
Have you been taking the medicine for 2 years? Do you only take it when the symptoms occur?