I'd recommend seeing a doctor immediately.
Is there someone around to call 911 if you pass out? If such comes on all of a sudden and without sufficient warning to "sit down or stop the car" you are at risk of other physical injury I believe.
I respond mostly as I am surprised there has been no response in 14 hours from your posting the message. It may be no one, myself included, has had the symptom scenario you describe.
I believe that any time you feel your heart beating strangely/along with passing out, you should see a doctor. I think that is the "rule of thumb" with doctors too. If you pass out due to an arythmia then you should have some tests run to make sure your heart is okay.
sounds almost like atrial fib.. My husband had those same symptoms but he did not pass out he just got light headed and he ended up in the e.r and that is what it was. He is now on 81 mg of aspirin. Nothing too dramatic or deadly. They told him if it happens again he should consider the ablation. once he gets that he should be symptom free.
Of course you should go see a doctor. Anytime you pass out, for no apparent reason, you should go. AND when you have cardiac symptoms along with lightheadedness or passing out you should get checked to make sure about the connection. Make sure you see a good one!
Since your young, most likely it is not serious, BUT go get it checked out!. My son did this a couple of years ago at age 20. He found out he was allergic to a med he was on. Stopped med and all was great. BUT if he hadn't gone to Dr. he could of died. He hit his head when he passed out and fell to the floor. Luckily he wasn't driving his car or the forklift. He was at work. Also I did this when I was 19. Found out I had MVP. Not too serious but I needed to know, so I knew the signs so I could pull over in a car, or lay down asap. GO TO THE DR!!!!
I would def. see a Dr. and ask for a halter monitor this will be able to tell them what is going on when your heart races. some arythmias are not life theating but others are, may be nothing but why take the chance?????
Please let us know how you make out!