Lumbar protrusion is unlikely to cause rib cage
Rib cage is big - there are a dozen pairs of ribs. They enclose heart, lung, food pipe and so on.
It is difficult to come to any conclusion - unless further qualified. Where exactly is the pain? What is the character of the pain? What brings it on? What relieves it?...
An internist is the one to see.
You need give a good history and have a physical examination; possibly a few investigations.
Wishing you speedy recovery