What Causes Burning Sensation In My Lower Abdomen When Suffering From Diverticulosis?

I have a burning sensation in my lower abdomen, just above my pubic area. I have severe diverticulosis, but this burning feeling is relatively new (within the past five or six months). I have never been hospitalized with diverticulitis, but recently, my bouts have been coming closer together --often within a month of each other. Once I take an antibiotic, the lower left quadrant pain generally goes away. I did consult with a gastroenterologist several times and have had several tests (two CT scans, urinalysis, endoscopy, recent colonoscopy), but I haven't gotten a satisfactory answer about this burning sensation. I even saw a surgeon in Albany and asked about bowel resection, but he didn't seem to feel I needed it at this time. However, this burning occurs nearly every day now, and I often wake up at night from it. I am 73 years old and otherwise in quite good health, aside from some lower back pain. Any suggestions or reaction?