Keep becoming breathless/heart pounding while relaxing?

I keep getting completely breathless and having to literally open my mouth and pant and my heart starts pounding so hard I can feel and hear it.. Its like when you've been running and stop but it happens on random intervals when I'm relaxing watching TV reading a book being on the PC or even lying in bed been going on a week what could it be? I don't want to risk going to the drs and making a fool of myself with it being nothing if it's of any interest I am late 20s and just went through a heartbreak