I Had Surgery Last Year For Diverticulitis That Had Become

I had surgery last year for diverticulitis that had become abscessed they removed 13 Inc of large colon. Then the pain came back in my abdominal area they did a colonoscopy today and said no infection all was clear. But I still feel bloated and have abdominal pain no fever an no blocks .yet I have no BM with out medicia n so I stay flushed to prevent this an still pain. WhY What can they not see in a colonoscopy