What's going on with my heart?

There have been some really weird things happening to me.The oldest problem I have is that sometimes,my heart will speed up for a few beats and it will hurt.This only takes a few seconds,but sometimes they really hurt.I’ve been keeping track of them.About three or four every two to three weeks.Then one day in my fifth hour,I was feeling REALLY bad.I had to go to the school nurse for nearly an hour.I had a pounding headache and for some reason,I sort of saw stars out of my right eye for about five minutes.I asked this guy to look the area around my eye,and he said it was really swollen looking.I went back to class,but I was dizzy and sleepy.In my sixth hour,I fell asleep for most of the class.(Thank goodness,my teacher was playing a video and she didn’t notice).Then Tuesday,I was in gym and we were playing this game called Team Handball.I was goalie and this one person threw the ball and I accidentally slapped it.The ball slammed right into the palm of my hand(the guys at my school throw hard enough to take someones’ head off!!!).I saw lots of stars.I could barely see someone three feet in front of me.And my ears were ringing loudly.The only thing I could hear was my breathing.Could these things be linked? It’s scary!!! What’s going on? I’m going to the doctor about the heart thing in a few days.