Suddenly My Heart Starts Racing And I Get Light Head. What Could Be The Reason For This?

I ve been having trouble at work in that last couple months. Twice, I ve had these attacks while working. They come randomly, usually when I work for long periods of time. My heart will start racing, even though I haven t done any physical activities that might raise it. My heart beat has a pounding sensation on my chest , and it also feels like I m being chocked. Also, I get light-headed and feel like passing out. I have to take deep breaths in order to decrease the effects (So the symptoms are still there, but not as serious). They have been so bad that I ve had to call out for work. My friend says she has SVT (supra-ventricular tachycardia ) and that her symptoms are alike mine and I might have that. Any thoughts or comments will be nice. BTW, my parents are having issues with the insurance, so they didn t take me to the hospital when it happened.