Can a old crohn's disease flare up (bloody stool) flare up again that causes bloody stools to come back weeks later while i have a 3 rib break?

Yes.: Crohn's disease is a chronic illness associated with inflammation anywhere in the GI tract, typically the small intestine or colon. It can be episodic, responding to a course of treatment only to recur again months to years later. You should have a GI specialist you see regularly. With return of bleeding you need to contact your doctor to discuss treatment.