Help with symptoms

Hey all. I am a 59 yo male that has had IBS-D since I was about 20 yo. My issue is in the last about year I feel like I am getting sick about every month to month and a half. It feels like I am getting sick, kind of like flu symptoms and I get bad diarrhea. It usually does this for like 2 days. I take Cholestyramine. I only take it 1 time a day when I get ready for bed. I have tried taking it more but does not help. Anyone ever experience something like this and what you did to help it. I haul oversized mobile and manufactured homes and unfortunately if this happens during me hauling, I cannot just pull over anywhere to do what I need to. Really like to try and at least get this sick issue to stop if I can. I hope it is not age related. I have tried several things over the years to try and get rid of this IBS like fodmap, seeing a natural doctor who put me on strict diet and natural supplements, carnivore diet and more with no success. Any help appreciated. I have never found exactly everything that causes me issues. I know there are several veges that cause me issues now and peanuts.