Oh what we have in common! Like yourself I have CD. But the RA I've been dealing with longer. The joint pain is very very severe, and the CD arthritis only flares up the RA (it's the icing on the cake right?)
I don't know what your physical capabilities are, but I'm no SUPER DUCKY! (you go girl)...but I do know that exercise is CRUCIAL.
Now, I can not go to the gym...or a matter a fact do too much of anything for too long! The exercise I suggest for those in very bad pain with joint problems are exercises that promote maintenance of the joints. Which are very simple. No marathons or power lifting!
Take first in consideration that a little goes a long way, and also take note as to when you're body is at the best. Like maybe not first thing in the morning, but say right after dinner or something; a walk is excellent for the bones and joints and say a light streatch afterwards and range of motion exercises (shoulder rolls, neck, hips, ankles).
That's pretty much all I do. Walking whenever I can, for as long as I can, when I feel I can do it.
When we read about exercise being good for arthritis, they're mainly focusing on 2 things: keeping weight under control (the less one weighs, the easier it is for the joints) and to prevent contraction of joints and limited range of motion.
I know, "I feel so crappy and can barely get through the day...how can they want me to exercise??!!" I feel that the simple things are great at maintaning the joints, and should you feel great sometime...go all out!! Weight bearing exercise will further help the ligaments and support the joints (can start out with 2 pound hand weights).
Personally, I've some bad mobiltiy problems some days; and on those bad days, I count doing the laundry as exercise, playing with the cats too counts. And I don't beat myself up about it. And when I get a good day, I walk an extra few blocks.
Depending on you own limitations and endurance, exercise of any sort, even a little a day...will benefit arthritis and prevent complications.
What are you doing now to keep flexibility? Are you able to walk and get about alright?
The best to you!!