If the heartbeat becomes very fast and the hands and feet beomce cold (I often used to have this condition) then write on a piece of paper and tie on the chest

لَاحَوْلَ وَلَا قُوَّۃَ اِلَّا بِاللّٰہِ الْعَلِیِّ الْعَظِیْمِ 

If you tie it in the morning then it becomes normal till the evening and if you tie it in the evening it will become normal before morning.