Just as the one other person on here stated, I think you should look into Gluten intolerance. I suffered just as you did, big time. Then, I cut out all wheat, barley and rye. My symptoms improved a huge amount! Im not completely better yet, but so much so, that I know I am intolerant of gluten. The IBS is almost gone.
I have had exactly the same problem for years....some days I can't even think about going or I will have to go. I find Lomotil is effective and use it especially for travel where no washroom is available. Please know that you are not alone.
Just a quick note to say hi! hello my advice to completely avoid eating wheat products it will definitely help u lot.