Feeling of earthquake in back of head, sometimes palpitations in back of head and legs?

There is a thing: called "exploding head syndrome", which is a type of headache. It doesn't usually cause strange feelings in legs though. It seems possible that you just have a lot of anxiety about something, but nonetheless, with any severe headache and other unexplained symptoms you should probably seek a medical opinion. When you do, just describe the symptoms. Don't use analogies "feeling of earthquake".