I've Been Experiencing Times Of My Heart Racing Like It's

I've been experiencing times of my heart racing like it's beating out of my chest off and on for the past couple of months when I haven't even been do anything to exert myself. Today it has been worse so I decided to check my blood pressure and it was 125/80 which my blood pressure has always ran low 110/60 and that's been pretty recent. What might cause this and when should I go see my doctor?