I'm confused!! If you think you are having a heart attack, why are you on here typing messages? You should be in ER having tests.
Tell your parents ASAP! They need to know what you're experiencing, and get you to a doctor.
My husband also has the chest problem like yours (pectus excavatum). The bone can put a lot of pressure on your esophagus and cause pain if you have any reflux (indigestion) at all. Laying down can even make it feel worse. Are you eating well, under some new kind of stress?
It's not likely to be a heart attack but it sounds like you're uncomfortable enough that you should have it checked out by the doctor. They may ask you to wear a heart monitor for awhile to see what's going on in there. Or maybe have an echo done (that's actually pretty cool). There's no need to suffer like this. Ask your doctor so you can feel better.