I've come across an excellent one, it's called primadophilus reuteri, Natures Way brand and have no more major urgency and no more "feeling" of incomplete evacuation. Also, no mucus!
As some of you may know I have CD (crohns disease) and highly suspected of IBS as well. This stuff has been fantastic, today I've only had one bowel movement, and that hasn't happend in over 14 yrs.
I use the powder, but you can get it in tabs too, but regardless, they must be kept cold to maintain it's potency.