What are coastal countries?

Do you mean "costal chondritis"? If so, that means inflammation of the joints in the sternum where the ribs attach to the centerpiece of the chest (sternum) in front.

With this, one can have chest pain especially when stretching the arms, breathing, or pushing on on the front of the chest.

Typically goes away over time, and is relieved by anti-inflammatories-- like Motrin/ibuprofen.