Have you done tests for your thyroid gland function (hyperthyroidism or over active thyroid gland produces such symptoms) and complete blood count (to rule out anemia)? If yes and they are normal, in addition to normal heart exam and tests, then these are most probably symptoms of anxiety precipitated by ongoing non-resolving stress. Avoiding the source of stress, or minimizing it, or trying to alleviate stress (yoga, sports, hobbies, meditation, relaxing natural herbs etc.) are recommended to help relieve your symptoms. Should these measures prove ineffective, you may want top consult a clinical psychologist who teach you with ways to cope with stress.