Sudden fast heartrate ,left hand pain,dizziness,breathing difficulty,often comes on and off....normal bp and normal sugar?

You should see a doctor, preferrably a heart specialist, for possible heart rhythm disorder. They would do tests for you, in the meantime take note of what you are doing when it happens so you could adequately inform the doctor. There are different medications and managements depending on what they find. If you are taking stimulants like coffee or street drugs stop and take adequate water.