Hi doctors! i'm a 31 old male. I'm 70m tall, and I weigh 80 kilos. I have no known medical conditions. I have been suffering from a deep muscle tightness in the left side of my upper back. Sometimes when the tightness becomes intense it spreads to my my neck and chest on the front and causes my heart to beat rapidly. I feel out of breath. Sometimes that tightness also develops into pain (from mild to severe). When I take a deep breath or swallow while eating, I can sense that certain something in the left side of my upper back. I have been to doctors of all specialties here and none of them have been able to figure out what is wrong with me. I'm so confused :(please help!