Two nights ago, while laying in bed, I felt what seemed like a muscle spasm or twitching on my left side, under my heart. It continued into yesterday, where it was happening frequently and then would stop, and then pick back up. Later in the day it stopped happening for the most part. Today, it has started back, but not a whole lot. I have some tightness near my left pectoral muscle. Is this something I need to be concerned about? I have no underlying health issues, have always been really healthy. I m 22, 6 2 , 180lbs 12-20 body fat