Potential heart problems?

I am a nineteen year old athletic, healthy male. I currently don't have any particular stress in my life, which is why I can't quite understand these symptoms. About two weeks ago, I was sitting in class and became very aware of my heart pounding in my chest. Not that it was necessarily beating fast, but it was a very forceful heartbeat. This went away after about five minutes and has not since returned. Last night, however, at about 3 AM, I woke up with a type of pressure/pain on my sternum/heart and had shortness of breath. After getting up and standing for a few minutes I was able to return to sleep after propping myself up on some pillows. Today it is giving me mild discomfort when I burp and in such instances. Needless to say, I have no idea what to make of any of this, so any feedback at all will be helpful. Is this something worthy of seeing a doctor? Thank you.