Yes, I had a colonoscopy which diagnosed the diverticulitis - I had been getting quite extreme lower stomach pain and I was even passing blood. Blood and stool tests showed inflammation. The colonoscopy investigation was done because there is Crohns and Ulcerative colitis in the family and they had to check what was actually going on. Fortunately I didn't have either of these conditions.
If they already know you have diverticuli (which are very common) and they have become inflamed, then you may not need the colonoscopy.
I wasn't given antibiotics but with hindsight I probably should have had some as the infection could have worsened - I had awful aches and pains through my hips and legs, my pelvic floor throbbed and it was very uncomfortable when I sat down.
I dragged myself out for walks every day, regardless of how I felt. Hope you feel better soon. DG x