Hi there. I am a 20 years old female. i exercise regularly. Today for the first time I have experienced difficulty breathing during a run, after I stopped running could feel my heart beating very fast, which continued for about 10 minutes, something that i have never felt before. It almost felt like my heart is going to escape my body. I am concerned as I have never experienced anything like this before. I drink coffee occasionally, do not smoke or drink, my diet is well balanced and I could call myself a healthy individual. What could be causing this heart palpitation? I am scared to run every again to not experience such uncomfortable and scary feeling.