When the flare ups come from nowhere...
I'm a 49 year old male, carrying 15kg too much, and my first experience was back as a 20 something in the early 2000s. I'd been away on a trip when I contracted gastroenteritis which laid me out for a couple of weeks, and after that I struggled with IBS-D and it took months to work out what caused it.
Looking for a root cause
The doctor dismissed me, told me to lose weight, and for a while I couldn't tell you what would cause a flare up. I kept going back to the docs, and eventually he prescribed me an antidepressant, rather than try to get to the root cause. I've had allergy tests, days when I can barely function, and days when it isn't an issue.
I changed jobs, which actually had a really positive effect, and would get through months at a time without a flare up. In 2014 I had a really bad episode which resulted in me having to have a colonoscopy (all clear) and the episodes remained sporadic. I'm in one now I think, where it's more IBS-C. Coffee forces me to go to the toilet, but I never feel that I'm finished, as it were. More blood/stool tests...
Do you have a good understanding of what triggers your flares?