Hi i am a 21 year old female. I have a normal heart rate and blood pressure and have no history of heart disease. I have a normal weight. Since the past many months i have been experiencing palpitations. I got them evaluated by the doctor. My blood tests, chest xray, ecg all came out to be normal. However since the past two days i have been having difficulty in breathing when i lie down at night. It's not too much. Just moderate. However i have read online that difficuly breathing while lying down can be a sign of heart failure. Please help