Oh yes, I've had gut problems for 7 or 8 years. I put it down to a very stressful couple of years with illness/bereavements of close family members.
I went low carb nearly 4 years ago, which solved the acid reflux and bloating problems, but I still have irritable guts!
I had various tests done - bloods, stool, ultrasound and even a CT scan (stopped short of a colonoscopy) which showed nothing untoward although I do have diverticulae in the transverse colon, but I don't think that is the cause.
I think we become less tolerant of certain foods as we age, for me it is sugar, wheat (fructans in wheat) and onions definitely don't agree with me.
It becomes difficult to know what to eat sometimes, as sometimes food tolerated one week, isn't tolerated the next!
It is also thought that people with IBS suffer from "visceral hypersensitivity" (google it) where the colon reacts more dramatically to food passing through it.
Over the years, I've spent a shed-load of money on various supplements, which haven't made much difference (or if they did, may have been a placebo effect), and have a cupboard full of various pills and tablets.
@Fennel, diverticulitis is inflammation of the diverticulae "pouches", and should be treated promptly, as infection can in some cases lead to peritonitis, and surgery.