I take Asacol a sister med to Pentasa. This medicine is an anti-inflammatory for Crohns. I don't see why your doctor took you off it either. Its a very mild medication with little to no side effects. Also, as far as stopping Pred you can't just stop it. You have to slowly wean off of it. I would not make any medical decisions in this case without talking to your GI. They are the Crohns specialist not your family doc.
For myself, the Asacol helps to keep the inflammation down and has helped me personally alot. Hope you get feeling better soon.