Describe your pain. I'm interested, because I have the same issues.
What sensations do you feel? Burning, aching, poking, prodding, zaps, etc.
Are the sensations all over or one sided?
Are they worse upon movement?
And when you say "mid-back", where exactly is it? I get mine both above and below breast level, but in my back.
And yes, I struggle with the is it lung cancer fear, although it's essentially ludicrous to think that.