I have this exact same feeling! I have had it for the last few weeks and it scares me so much, it is like a sharp pain in my left side of chest and it freaks me out which causes my heart to pound in response! When I lie flat on my back it seems to go away..and when I sit or stand yeah it feels like pressure and comes back! Scarier is that I get the pain sort of shooting in my left arm a bit too which REALLY scares me. I am only 21, so I always try to convince myself that surely I am healthy and too young to have a heart problem! Although I suffer from serious anxiety and stress problems and this pain seems to get worse when I m stressed. And I have a really bad back at the moment which I think is causing some of my chest pain, it is all so scary. Likely anxiety, but still scary because I have not had my heart/lungs/chest checked ever. (
I have had the same pain for years from armpit to my left side above my breast. It had stopped when i stopped doing excessive lifting recently i started experiencing a very scary sharp pain above my left breast towards center comes and goes it worsens when i rest whether be laying down or sitting in chair there is no bump i am self checking but i am wondering if it could been when i was stretching. My arms if i may have torn anything.
Look up cardiac chest pain. it is probably that. Or possibly even Angina or Pericarditis. Definitely ask your doctor about those conditions or look them up and see if that #39;s what it may be!
I also forgot to mention Pancreatitis. that also causes what your describing. Hope you figure out what s wrong and best of luck!