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Have you got an ECG done. Has your heart been examined by a Doctor to rule out any problem. If there is no problem detected it could be related to Anxiety
disorder which is very common. Also since you haven't been getting sleep it indicates Generalised anxiety. Eat healthy, fresh fruits and green leafy vegetables everyday. Avoid junk food. Drink plenty of water. Exercise daily to keep fit and have overall well being. It would be best if you consult with a Psychiatrist
to get best benefit and relief from these symptoms.