I had some of the same issues and my doctor told me two things. One my weight could cause stress on my muscles, including the lungs, cutting off blood circulation. This cause pain, difficulty breathing, and numbness. Also I fell down a flight of stairs 3yrs ago and broke a rib that healed wrong. I never even knew that, I new it hurt when I fell, but just went to bed and didn't think anything of it. Anyway, when I get excerted or over stress/anxious it cause trouble breathing and pain in my shoulders, arm, and back. Don't know if any of these could apply, but an idea. Something else I forgot was that the spine in my neck actually curves backwards, causing back and shoulder pain often, especially when I work out.
Thank you for your response, I am making an appointment with a pulmenary doctor to rule out the lungs. If that is ruled out I will look into getting treatment for Costochondritis. Is that something I could have for all of these years with no further symptoms or progression?