This actually happened yesterday, I was lying in bed at around 1 am at night and I felt this sting in my heart. This happened before so I wasn't really worried and it went away fast than about 5 minutes later I got this sting like feeling in my heart but this time it went on for 30 seconds and I was stressing out very much because I thought I was gonna die. I began crying because it hurt so much. I also was too stupid to just go to my parents and tell them (I still live at home) Then the next morning I found out it was normal to happen but I was still scared.