Re: abnormal rib cage shape?
Sounds like possible scoliosis to me, but you should probably see an orthopedist, or at least your family doctor to check it out. I have slight scoliosis, which was never detected when I was young, but has caused some problems in my ribcage this past winter. (I'm 50) My ribs were curved up and over the others, due to a rotation in my spine, because of slight scoliosis. But this caused severe pain. Even a slight curvature in the spine can progress over time, and is best treated when you are young.
I had a hard time getting any diagnosis, even with xrays & MRI, and finally got help from a physical therapist.
But if this is something that just showed up as you grew, you should get it checked out. No sense having worse problems somewhere down the line.
Hope it's nothing and just one of things that makes us all unique.