persistent chest pain

Hi im 21 year old male.Im having this pain in my chest and my left shoulder for quite a long time now.It just started one day .Except pain there are no other symptoms like out of breath,palpitation,weakness,fever ,irregular or fast beating or pressure on chest.Actually I usually experience pain only when im idle.During my normal routine or exercising there is no pain.Infact exercise relieves my   pain.The pain  is in my shoulder and left of my chest .The pain  is continuous .
I dont smoke nor drink.In my family  my fathers brother is only heart patient.He has some problem with his valve.As for me i dont have any other problem except this nagging pain.
this  pain stress  me out .There are times when i think that my heart will stop and i will just die like that.