I am 22 years old female and for the past few months I have been experiencing difficulty breathing as if my lungs don t take air in to their full capacity. I also have pain and feeling of pressure on my chest as if some heavy weight is placed on it and I noticed that this usually occurs when I am emotional or stressed. I sometimes experience acceleration in my heartbeats too. I have seen a doctor who tested me for asthma, did an ECG, chest x-ray ESR, and TSH, but they were all normal. I have family history of heart disease, sudden death, asthma, Parkinson s and cancer. What could be the cause of my problem?