Help for IBS-D flare ups?

Okay first off, asking on behalf of my boyfriend. Second, I know triggers are different for everyone just like dyslexia is different for everyone who has it. Suggestions for flare ups? He seems to have pretty severe IBS-D. Sometimes he'll go 2 weeks and according to him on a 1-10 scale 7-8. Most days he says 5-6. Probably 3-5 days a month he says 9-10 out of 1-10. Not saying he's lying and he is probably just used to it so has a high pain tolerance and I have terrible social skills reading body language and he's normally quiet, reserved, and calm, yet even 5-6 days he acts the same as 9-10 days. Maybe he's rating it different than I am, I don't know. We work at the same place, he comes into work, but then doesn't want to meet up for dates. Which I completely understand work is priority and I told him I'd rather see him on a better day and not have him force himself to keep his word going on a date just to be polite and go feeling crappy. Then I'd feel bad knowing he was forcing himself for me and he wouldn't be able to enjoy time spent together either I am sure. I've heard of FODMAPS, but dairy, caffeine, high fructose, greasy, fried, sugary doesn't cause things more than other days. Note: He just uses heat pad when it gets bad. Oddly despite the severity he finally went for meds, he's had IBS-D for over a decade. I'd think if it were that painful, I'd go in sooner. I know stress can be a trigger/factor. He doesn't take meds for anxiety or depression, eats a lot of fast food (especially taco bell), does not take probiotics and/or fiber, hasn't tried a TENS unit. He says he gets flare ups even when not eating taco bell and not stressed, but he doesn't open up and he keeps emotions bottled inside he doesn't share that stuff. He said he's on Levsin. Any knowledge of any of these others being successful for severe IBS-D: Xifaxan Bentyl, Buscopan, Enterosgel?

Help for IBS-D flare ups?
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