I am so very sorry to hear about your 15 year old son's heart murmur. I would definately seek a pediatric cardiologist for an opinion - which would include a echo.
My middle son (now 27) has a bi-cuspid aortic valve that was discovered when he was two. He had a heart murmur from birth but the pediatrician "spared me from worry" by not telling me about the murmur until it got worse. At his two year old well baby checkup I was advised to see a pediatric cardiologist.
Although his mumur is moderate, my son has had no problems and no restrictions - except that he has to take antibiotics before dental work and any time he has an infection that has "puss".
good luck with your son, your family is in my thoughts and prayers. Please feel free to pm me if you would like to talk.
