I too have IBS with diarrhea. Can feel your frustration. I have had it for over 10 years, but was diagnosed with it 3 years ago. My doctor tried all kinds of medication, but they didn't work. (Bentyl, and Lomotil included). Diet didn't seem to make a difference, as well as taking supplements. I had been to see my doctor constantly due to the pain and diarrhea that I was having with IBS.
I too have diarrhea several times a day. I found it hard to get out of the house sometimes, and for me, I had to quit work last year.
I ran across some information on another forum about a medication called "Lotronex". I asked my G.I.doctor about it as nothing else seemed to work. He seemed enthusiastic about prescribing it to me (don't know why he never thought of it?). He said that he had to take a special information course on this drug. I have to warn you that it was pulled off the market by the FDA several years ago because it was given to those with IBS-C and caused those people to get bowel ischemia resulting in some deaths. The FDA put it back on the market a couple of years ago, and now only prescribe it for those suffering with IBS-D. If you get any kind of constipation, you have to stop immediately. Your doctor is supposed to monitor you while on it.
Fortunately, I have been doing real well with it. No side effects, no constipation. It doesn't cure IBS, but I am actually able to run my errands now, without worrying about stopping at public bathrooms. I have more normal bowel movements.
It's costly, and even though I have insurance, my copay is $50.00 for 30 tabs. (My pharmacist told me that it would normally run $500.00 a month). Worth it if you can get part of your life back.
Anyways, this worked for me. Good luck with your visit to your doctor. I wish the best for you.