I have this squeezing throbbing down deep on my chest that is likened to someone having their hand in there squeezing something. Only way I can describe it it's like a narrowed area of a pipe and where the pipe narrows pressure builds up at the entry end. This is amplified with sluggish intense throbbing for example when I first stand up. I feel dull pressure in my chest most of the time, at rest or not, and I have horrid fatigue, lightheadedness, especially during exercise, and early heartbeats that I've never had before. My echo, EKG chest Xray and blood tests were all normal. This illness , whatever it is, is bringing me to my knees, please help me.