I Am Have Been Taking Pain Medication For Two Years

I am have been taking pain medication for two years for back surgery which resulted in nerve damage that causes severe pain and burning in my buttox and leg....anyhow I have always had a sluggish bowel, I go once every couple weeks, I have noticed recently that when I finally go and if it is hard there is a lot of blood on the stools, bright red...also what looks like flesh flakes in the bowl...my rectum feels like glass shards for a couple days later, even passing gas is painful....I had a colonoscopy about five years ago and all was fine.. I have also had hemorroids banded in the past....could this be the result of internal ones causing this larger amount of blood? ...