So I have had pretty painful chest pain and shortness of breath, as well as it being increasing hard to exercise- getting sweatier, getting out of breath quicker, etc. I went to the doc and was diagnosed with costochondritis, even though my pain was more dull and aching pressure than the sharp pain the costochondritis leaflet described. I took advil almost everyday and I was in pain almost constantly. It started to fade a bit, and then just recently I went on a plane trip- on the way over I completely fine, but on the way back my chest began to intensely ache on the left and right sides, and I felt very dizzy- the airport was spinning and I could feel my head throbbing. It was not fun. When I got home I slept and the headache went away, but the chest pain woke me up in the night and has gotten increasingly worse. I went to the doctors yesterday and got an ECG, Chest Xray, and had my blood pressure checked standing, and sitting. My urine was tested for the dizziness, to check if I was dehydrated. Everything came back clear, except an innocent heart murmur that I was born with. The doctor gave me an inhaler, and told me to take magnesium baths, as it could be magnesium deficiency. I just got a really intense wave of the pain and a weird heart beat- I don't know how to describe it, it felt like louder, or something. Does anyone have any idea what this could be? Is there any chance at all that the tests missed something? My voice has been getting hoarser, and I have a small cough, if that is important. I'm a fourteen year old girl, 5'7, normal weight. Thanks anyone who answers, I'm pretty worried. Sorry it's so long. Also one last question, could the heart murmur be more serious than it seems? They said a cardiologist looked at the xray and said everything looked good, ECG was good too.