Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. There is a possibility of cardiac arrhythmia like psvt or atrial fibrillation, in which heart rate suddenly goes up and also suddenly decreases. Blood pressure falls during these episodes and one has dizziness, fainting, blackouts, sometimes syncope. Usually ecg is normal as it is usually done in between the episodes. ECG done during episodes will show abnormality. You will need 24 hour holter monitoring. So visit nearby cardiologist for these investigation. Also, hemoglobin and thyroid test should be done. ln order to abort such episodes you should try to cough hard. Is there any stress or anxiety associated. Till the time your evaluation is complete, you can ask your local doctor for tab ciplar LA 20 mg once a day. Hope this helps you and get back if you have any doubts.