When I broke three of my ribs, I didn't feel an immediate pain. But, boy, howdy, I felt it big time when I coughed, sneezed, or blew my nose!
I don't know what has happened. Maybe a strained muscle? I would think if I broke them from coughing I would have felt a real sharp pain immediately when it happened. I just woke up New Years Eve morning and they were hurting.