I have atrial tachycardia and have been on Flecanaide for about a week. I am experiencing a different chest pain to the previous pain I had, breathless, wheezing ,exhaustion after very little exertion. I have pains in my joints and sometimes feel I could just drop. Is this a normal response to the med?. I didn't have headaches before but am getting regular headache and sensitivity at the top of my scull.