I am a med student, so I probably imagine the worst with anything, but this definitely sounds like something you should get checked out--an EKG to check your heart, and definitely check blood pressure. I know doctors are expensive (I still avoid them, and I'm going to be one!) but this could be very serious. You are young--it is worth finding the answer now and staying on top of your game instead of having it bring you down, or interfere with your life for years.
And even if it comes back as nothing serious, at least you will feel better having an answer and some advice on how to deal with it. Peace of mind is still money well spent! And if it is serious, then you can deal with it now and and not have it turn really bad really fast on you some unexpected time in the future.
Go see a doctor. Let us know how it turns out, if you are willing to share. Good luck!