Question
I've had a tightness in my chest for a couple of years now, and when it gets
to be painful to inhale deeply, I can usually put my arms above my head, look
up, arch my back a bit, and what I THINK is my sternum cracks like you
would your fingers, very loudly. It's incredibly painful for a moment, but then
the tension in my chest is relieved at least for a bit. I've been to a doctor for
this, but was just told to take an insanely large amount of motrin daily and it
was basically just brushed off as me complaining about nothing.

I'm wondering if there's something specific this could be, and if I should push
my doctor to explore it further, or if its something I just need to live with. It
does let up sometimes, but most of the time I'm moderately uncomfortable,
especially when I feel like I need to crack it but can't quite get the right
position to relieve the pain.

Answer
I would suggest seeking out a good chiropractor.  It sounds as if there may be misalignment of one of the ribs, locking and causing tension.  When you get in the right position, it relieves the pressure a bit, giving temporary relief.  A good chiropractor should be able to assess and treat this, and help rehab the problem to reduce its' likelihood of returning.