is the tightness/pain near your sternum?
I experienced a very weird tightening sensation in my sternum a couple years back and didst do anything about it because I suffered from panic attacks. I continued like this until I had a panic attack whilst this tightening happened so got taken to the emergency room. I was found to be suffering from a mild case of costochondritis - an inflammation of the sternum.
this diagnosis lead to physio, medication etc for a year or so and now I'm fine! don't know if this is relevant in your case, but thought you'd appreciate some sort of reply.
hope all is well!