Hello Do you have associated vomiting, pain anywhere? Have you lost weight recently, any irritability, nervousness? Any breathlessness, chest pain? Are you taking any medications? Thyroid problems can cause palpitations (feeling that the heart is beating fast). Even anxiety and panic attacks can present in a similar way. There are other rare causes like heart problems, of pheochromocytoma which can present like this. I would advise you to see a physician as soon as possible to examine you and do necessary investigations to figure out the cause for your complaints and to treat it accordingly. Take care