My heart will randomly start beating hard (sometimes causes me to cough). It has only occurred the last week, and randomly throughout the day. I have not drank any caffeine, coffee, soda, energy drinks, etc. I only drink water and juices. I am only 19 years of age, no heart diseases are known in my family. I have not been doing any exercises that are new or different than normal. Is this an indication of an illness or something?