I m 19 and female. I have strange, sharp pain under my left breast when I breathe, a lot of acid reflux, but the pain goes away completely while I lie down. Pain is aggravated when I breathe while walking or sitting unless my left arm is raised above my head, stretching my diaphragm. I ve went to a doctor 2 years ago when I experienced the exact same symptoms- did an electrocardiogram, chest x-ray, saw a cardiologist- everything came back OK. Just found lots of gas build up in my stomach and my doctor claimed it could be a combination of gas with anxiety and a musco-skeletal problem like costochondritis. Now the issue has come back and last time it lasted over 8 months before I didn t experience any pain anymore. It s recently come back and to be honest, it terrifies me that it ll last as long as it did last time. What do I do?