Is it the heart murmer or something more serious causing the pain? I v had a heart murmur since i was born, it never gave me problems wen i was younger, now that i am a teen i have been getting these constant heart pains it feels like a knife stabbing me in the heart. im scared to go to my doctor im not sure if its the heart mumur. its just constant pains, iv had it for a while, and now the pain is lasting longer then usually, usually it lasts a min or two. and now im scared it might be something serious? what do you think it could be?