I am in exactly the same position as you, within minutes of me eating, and sometimes even while eating, I need the toilet. I won’t eat out anymore, I don’t eat breakfast as I panic that I will need the toilet on the way to work on the bus.
I had mine removed in 2007 and I really wish I researched it, we went on holiday to Spain last year and I could not sample any of the lovely food and could only eat in the hotel cause I knew there was a toilet near.
I was on that orange powder stuff you mix with orange juice (sorry cannot remember the name) but it did not help me. I take 8 imodium a day and even they don’t help most of the time.
A few of my biggest no no’s are lettuce, any dairy and burgers.”