Thank you for asking. I can understand the distress you are through. Your complaints are indicative of anxiety problem. Fear of specific situations, fear of something bad happening, persistent thoughts and  fear about such things happening in future, etc are few symposium specific anxiety problem. In your case it appears to be a panic disorder like case. Although a detailed history and specific information regarding the problem and associated symptoms is required for making a diagnosis. The further treatment and management can be advised only after that. It is a psychological problem and not physical.