Anxiety and Stress Come in All Guises

Take a deep breath!  It's excellent that you had the EKG done so that you can know that physically you are in good shape.  Now you get to take care of you on different levels.  It sounds to me like there are issues in your life that are causing you stress that you haven't yet identified or dealt with and your body is letting you know it's time.  Here are some suggestions to help you get through the moments when you're heart is either racing or you feel it slowing down:  STOP! (whatever you are doing) BREATHE! (long slow deep breaths... in through your nose to the count of 4, hold your breath to the count of 4 and exhale gently through your mouth... to the count of 4) FOCUS! (Is something going on that bothers you, upsets you or angers you, etc... ? Notice what may have triggered your reaction. Once you are aware of what has triggered your reaction it will be significantly easier to come up with effective strategies to deal with it. 

I strongly recommend counseling with someone who is experienced in mindfulness, hypnotherapy, stress management, or mind/body therapy.  You might also want to explore how neurofeedback can be helpful to you. There are a number of complementary services that can also prove beneficial to your situation.  Look into Yoga, QiGong, Massage therapy, Emotional Freedom Therapy (EFT) or Cranio-Sacral Therapy. 

It is imperative that you explore what it is your body is communicating to you with these symptoms so that you can feel stronger and more empowered.  I offer workshops and a variety of programs that may prove helpful as well.  Please just know that your body/heart is asking you to pay attention, and you have some recommendations here that can prove to be very helpful.  Know that you are not crazy, you simply need to learn new ways to address the issues that are coming up for you in your life right now.