Sounds more like IBS to me. I don't know if you remember 3 years ago when my DH was very ill and almost died. Well he had a severe bout of diverticulitis and had to have his sigmoid colon removed due to the extent of the diverticuli. It is fairly uncommon in the younger generations, which is why he almost died, as Doctors just don't think of it. He had persistant diarrhoea and he smelled sick after he had been in the toilet, like he had gastro. Seeing yours seems to be related to what you eat, then I would think something like IBS.

It is frustrating when the older generations go on about diverticular disease, as from what I have seen it presents quite differently in those that are younger. In DH's case he had 16 diverticuli get infected and burst. The regime he had to follow during recovery was very strict and quite different to what the elderly often have to do. Oddly enough he had to avoid eating a lot of fibre.

Definitely get a proper diagnosis. I suffer from IBS and have found improvement by working with a naturopath, so that is another path you can look at.