Diverticular.
Diagnosed with these years ago (pockets in the bowel) and having been settled for years, suddenly got a flare up and got gut ache. Started when I was driving the truck a couple of weeks ago and by the end of the shift my guts were killing me. Been trying to get the fat off my belly, reduced my carbs and I've stirred my insides up - GP says I need to eat a lot more fibre, so its back on the bread, beans and stuff like that.