when i am silent and alone ,Suddenly some thoughts comes in my mind and i starts to fell fear . When this happens i sweat in my head and the whole body and feel i go cold . Also i feel my breathing becomes heavy and tummy becomes tight. This happens when i am relaxed and not occupied with any work. The if i starts reading something or listen hard to music or play games on phone/laptop. then gradully that fear subsides down and i becomes normal.