Mine is IBS-d and flares up when I'm stressed (or sometimes even just in a hurry to get out of the house). Worse in the mornings, sometimes wakes me in the small hours.
Over the years I've tried Colofac, Mebeverine, Mintec, Spasmonal, a range of OTC remedies including Fybogel, Buscopan, Imodium and numerous herbal supplements. I've tried changing my diet - I've done gluten-free, dairy-free, FODMAP, low-fibre, high-fibre and vegan. I've tried cutting out alcohol, sugar, chocolate, caffeine and artificial sweeteners.
The doc suggested keeping a food diary which I did for about a year, but found no common factor that could be the culprit so I gave up.
Years later DH suggested trying again but this time use a spreadsheet. After six months I discovered that what I ate had very little to do with it. WHEN I ate was more of an issue. I stopped eating after 7.30 in the evening, and found that while my symptoms didn't go away, episodes were shorter and easier to manage.
But the major revelation happened when I revisited Fybogel. The first time I tried it many years ago (taken exactly according to the pack instructions - twice a day with meals) it made things a lot worse. This time, I only took one dose a day, after my evening meal. Crucially, I ate nothing else after that until the next day. MASSIVE improvement. Far fewer episodes, (about once a month instead of 2 or 3 times a week) and lasting typically less than an hour each time.
I swear by it now. I'm not cured but it's totally manageable and I've got my life back.