Sounds like a rectal spasm. They are lovely aren't they. The GI can give you anti-spasmotics for this. Usually happens to me in a vicious flare or when I've eaten something I shouldn't have. Try a liquid diet for 24 hours and see if this gets you back on track.
Dx'd Jan'06, 1st Resection 7/06, Predinsone, Humira, Imuran, B12 injections, Nexium. Secondary conditions: Psorasis, Acne, Fatigue, Joint Pain, Lactose Intolerant, gallstones, fibroid cysts, peri-menopausal.