In 2010, I was sent to the hospital twice for severe chest pain. The pain was centered between my ribs. After a couple of CT scans, nothing was discovered. It wasn't my heart, which was the first concern. To this day, they don't necessarily know what caused it. Actually, it comes and goes occasionally, but not so severe.
A specialist diagnosed it at Costochondritis and thinks it is related to my Crohn's. In fact, most inflammation you may have in one way or another is related to your crohn's.
If I experience rib pain, a couple of Advil usually takes care of it and it just goes away...