First question is...has it hurt for more than 6 weeks? Cracked or broken bones take up to six weeks to heal. (small bones 6 weeks and big bones 8 weeks for healing)
Bruised rib bones or sternum(center bone where all ribs conjoin in the center if your chest)are sore but cracked or broken really hurt and gives you sharp pain plus difficulty breathing.
Ultimately it brings on a shortness of breath because it doesn't enable you to expand your ribs which helps you breath better when inhaling and exhaling.
If your sore bone just developed somehow on it's own without an injury I would think about getting it checked out!
Myself, I was laying my fill weight on the side of a ladder as I tried to extend my arm out to paint and cracked my rib. I took nearly 6 weeks to finally heal! Another time I cracked my sternum after a big yawn and stretch! OW!
I am glad you asked this because my chest hurts like that too. I asked my chiropractor about it and he said it's like your back, sometimes you just need to pop your chest. So I did, and it felt great. I hope this helps you out.
It is nice to ask others about symptoms that they may have had that are similar to yours, but the bottom line is that you should see an actual health care professional as soon as possible. You only have one life and one body, don't take a chance on something happening to harm you. See a doctor immediately.