Thought I'd share my experience, had stabbing pain in back while sitting on the sofa looking down at some documents I was reviewing for work. It was between my shoulder blades, felt like it started when I had put my head down to look at the papers on my lap. The pain was like a band around my chest/upper back, heavy chest, pain in chest, short of breath and sharp pain when breathing deep in chest and back. It continued for 45 mins so I went to hospital. They did blood, xray, EKG and everything came back normal, they originally thought it might be a blood clot in my lung but it was ruled out by blood test. They sent me home with "maybe gall bladder or gastritis", it ended up being neither it was diagnosed by my Chiropractor whom I decided to consult when I googled my symptoms and came up with compressed spinal nerve. He knew all about it and asked me questions that I directly answered "yes" to all and he nailed pain points within seconds. He agreed that all other causes need to be eliminated beforehand but he's seen it before (experienced it himself) mostly in students who work from their laps (laptops, study books etc) and the head and neck are looking down at lap, recommends to always put a pillow on lap. I'm now returning for contiuned treatment to resolve.