Wow, ten years. That's a lot of suffering. I take a medicine from my doc called hyoscyamine, a tablet that dissolves under the tongue, once a day. It helps a lot. It is prescribed for some IBS people. The other advice here is good, too, the cheerios and whole bread. Drink plenty of water during the day, and do a lot of relaxed walking. If you've had diarrhea ten years, could be a particular food allergy is doing this, like milk or nuts or wheat or coffee. Also some meds cause it. Don't eat out so much, don't drink too many sodas.
I've been having the same problem, but I've found that if I eat small meals and lots of fiber and plus my Imodium everyday it is in better control. If you eat whole grains bread, as an example it is better than white bread. And also if I don't get my veggies and fruits everyday ti screws up everything.
I had diarhea on a daily basis for years. I also went through the colon test and everything was OK. Now I take an Imodium everyday and started eating a bowl of cerial, I do cherrios, and I do not have the diarhea nearly as much. If I don't have my cerial I go right back to having diarhea. It's just a thought and worth a try if you don't already eat cerial