When we have a condition like Crohns it's easy to attribute just about
any pain or symptom in the abdomen and torso to it, but sometimes the cause may be something mundane which anyone can get. If your rib discomfort is aggravated by movement as you say, that sounds like a muscle-skeletal thing, which a lot of peolpe get -- simpl muscle pulls and strains between the ribs can take some weeks to heal because we can't really rest them, and they can be annoyingly uncomfortable. Cold be a lot of things, maybe Crohns related and maybe not, so you are doing the right thing to have it checked.