What Causes Blood In Stool While On Medication For Diabetes 2?

Hi there, Would like to know, recently have been having bowel movements and there has been blood in my stool. I know what Hemorrhoids are, been there and am doing that but, this is different. This blood is in my stool, I think. I had a bladder and bowel repair years ago but have not had problems until now. Nothing hurts, but I do have a discomfort once in awhile in my lower right abdomen. I am a diabetic 2 and have been taking Metformin for the last 9 years. Metformin always gave me the (runs) but was told it was normal for some people..... Can you give me an idea what I should do? Thank you in advance.