Have you noticed a change in degree of pain according to what you have been doing? Are high-G manoeuvres worse than inverted flight, or vice versa? Where is the pain? Is it all over or localised? Is it an ache or stabbing? Is it the same in all aircraft?
Have you tried adjusting your sitting position? You could try loosening your shoulder straps a little or folding a towel in the small of your back.
Sorry for all the questions!
