Heart feels like it's being electrically shocked...Any advice?

So I put this in "heart conditions" but I really have no idea whatsoever what this might be.  I'd really appreciate any advice any of you can give me!

I'm 28, female, have the blood pressure of an elite athlete (whatever that means--that's what docs have told me), normal cholesterol, overweight but losing it (was 150, shot up to 250 while in school, currently 215 and well on my way back to normal thanks to lots of hiking and home cooking--very healthful weight loss), and generally pretty healthy.  I've got great muscle strength and aerobic fitness these days as well.  

My only health conditions consist of patellofemoral syndrome (a kneecap that doesn't stay in place too well), depression (happily on Wellbutrin 300mg extended release for 12 months now, no problems), and I was diagnosed with a slow heartbeat at birth, but it hasn't caused any problems (and no doc has ever mentioned it since, so for all I know it's normal now).  

About 8 months ago I began experiencing the sensation of an electrical shock in my heart.  It literally feels like a freaking cattle prod poking me or going off inside me.  And I know where the heart is and it's definitely there (unless my nerves are completely screwing with me).  Occasionally I wonder if my left hand feels sort of weak after that happens, but I think I may be imagining that.  Anyway, I get "shocked" once every couple of weeks, sometimes a few times in a row for a couple of hours.  

It's painful, it's freaking me out, and I'm between insurances for a while.  I'd love to hear any suggestions/ideas you guys and gals have.  I've searched and searched the web and can't find anyone with the same sensation and no other symptoms.  Looking forward to hearing from you! :)