How do I know if it is chest or back pain?

[SF2223]

I'm 31 year old male, former smoker, with crohns disease.  for a few months I have had worsening sense of deep chest pain very central below breast bone. I feel it when I deep breah (on the inspiration mostly) and when I hunch forward and sometimes lying flat on my back.  because it is so deep I think it is either at the spine or the back muscles.  That, plus since it seems positional, I'm assuming it is muscular in nature, bad posture maybe. But given that it hasn't gone away and it is so deep in my chest, I'm not sure if I should worry or what I could do.  How do I know if this is back pain or something more sinister?

[ed34]

I think you should have a chest x ray and blood tests. At your age most muscular pains
should vanish after a few days, not worsen. What you don't mention is if it worsens if you
exert yourself. If you say jump on the spot for three minutes, does the pain worsen and
do you get short of breath.