Dagger makes a good point. I'm pretty sure no studies have been able to show any specific benefit of Omega 3s for Crohn's. However, they do so many great things for the body that they might be worth considering.
Culturelle is a pretty good probiotics supplement. We found that even commercial yogurt helped to balance the gut, but prefer to make yogurt at home, aged at least 24 hours, because it is far more powerful, "pure" (no additives), and because the lactose has been broken down by bacteria.