DO address this with your parents, pain is a symptom. Regardless of what it is, they need to know so that they can rule out any problems you may be having.
Heart problems do not cause stabbing pains so you are just fine. If you are still scared, try telling your parents about how you feel. You do not have a serious problem from what you are describing. Kids who have serious heart disease which causes chest pain are not living a normal life; they can't ride a bike, participate in gym class or 'hang out at the mall with friends'. They can't walk across a room without being in pain. Even having said that, VERY FEW kids with heart disease have chest pain, probably only about 3-5%. If you were having these kind of problems, you would certainly know it and your parents would have no difficulty seeing the problem in you. Go enjoy hanging out with your friends at the mall.