Sharp, sudden, when you bend/grab--Ah, sounds like you put your back out a bit or a pinched nerve, or both. I can't recommend Bowen therapy enough, especially for IBD'ers with weak connective tissue and likely adhesions.
Bowen comes out of Osteopathy, works on tendons only, very gentle and calming -- likely to help with your CD symptoms too, though the day after you may feel worse, you'll notice a difference in sensation, after, 2 days after you'll be much better. May take a treatment or two, or three, depending on how out it is. It got me walking after a year lying down and cured me of migraines -- hand to head.
I really cannot say enough good about this body work. I've tried many and this is the only one that actually helps me in the long term.
There's a practitioner search, hope they have some one in your area (* means more training and often Naturopaths trained in it, go for and ND if you can -- tax deductible at the least) Also, there are other sites, good to google Bowen and your area, country. Not all practitioners post info on all sites...
Watch how you bend to grab stuff until you get it fixed.
(once I put a tendon out in my ass, from pooping in the wrong position, try s'plaining that one..)
CD 24 years. Multiple surgeries in past 10 yrs. 4 year Illeostomy. Mesh rejection. Too close to death, twice. Large inscisional hernia. Perpetually underweight. Short bowel syndrom. Have used a variety of complementary medical therapies. Highly recommend Bowen Therapy as the best body work. Take me vites. Started Low Dose Naltrexone March 27, 2010. Got married for the only time 2008. Survive because of the love of good friends, and because I can. Happy to be alive. IBD needs more awareness and more voices willing to speak up. BE well.