I Have Very Painfull Chest Pains Every Once In A While. I Was Born With A Pretty Big Heart Murmor.

hi i am a 14 year old boy and i have very painfull chest pains every once in a while its usaly around the bottom part of my left rib gage and it is real fast and doesnt last long but really hurts also i was born with a pretty big heart murmor but never have had it checked since i was little since doctors said i shuldve grown out of it and the only other medical condition i can think of that my family has is high colestoral and i had a tumor in my esophogas about 3 years ago but it magicaly went away when i went to go get some mor biobsys done on it can any1 tell me y dis is happening and dont b afraid to tell me truth if ima die ima die so idc just tell me wat it culd be and wat i shuld do. i didnt know where i shouldve posted this but i hope this was rite catagory