Why I Am Having High Palpitation And Shivering Organ ?

everytime i have to do something new, even something as small as talking to a stranger or submitting my file to my teacher i start shivering very badly and my heart starts beating very fast, as if it will thump out of my chest . i was never such a nervous person,i have been a stage actor all my life so question of being a nervous person innately doesnt arise. this has started happening recently, gradually increasing since a year or so.can anyone tell me why this is happening and how do i get it cured? i am not a smoker or an alcoholic. it has increased a lot after my mother s death in february. someone please help me, i think hundred times before even calling up anyone i dont know for any query also.