So tonight I was casually watching youtube videos like I always do. I came across this particular video that educated veiwers about HPD. Than at the end of the video this song started playing and I felt a sudden wave of emotion. It made me think about the people I used to hang out with and we were friends at the time. I shed a couple of tears but I don't understand why I feel like this for a brief moment? Its been 3 years since the traumatic event, I'm over it and I moved on. But sometimes I get flashbacks of the events that took place in my life. What does it mean when this happens?