What Causes Lower Abdominal Pain?

I have been complaining about abdominal pain on my left side for years now and sometime excuriating lower pain in the small bowel. In 2009 they found one polyup in the sigmoid colon and took it out. I was diagnosed with divertiticulosis of the sigmoid colon with large and small mouth diverticular. After researching I found that constant pain on the left side consitutes divertitculitis and not divertitculosis. I'am wondering if all this time I could have divertitculitis instead of divertitculosis. I'am also wondering if I have an infection in my gut due to the excuriating pain I experience when some foods goes through my system. Sometimes the colon scope can give you infections in colonoscopies and endoscopies. I'am scheduled for a 15 core prostate biopsy and fear sepis infection due to uncertainty of my sigmoid colon condition. Your input would be greatly appreciated.