Change in Bowel Habits...

I am a 36 year old insulin dependant Diabetic.  I have been a brittle diabetic for 24 years & now use a pump.  I suffer from Chronic Disease Anemia, Diabetic Neuropathy, Diabetic Retinopathy Disease, as well as Arthritis, Flex Tendonitis and most recently diagnosed with IBS & Fibromyalgia.  Generally, I feel great, but when my iron & haemaglobin levels dropped, I was put on iron pills.  That was horrible.  I had never experience constipation or hemroids before in my life until taking the iron.  I see a Haematologist & my haemaglobin levels have started to come up, by eating better.  My concern, is that even though I've been off the iron for several months, my bowel movements have never gone back to "normal". I'll go one day, not the next, go the next & then not go for a couple of days.  The time has never really changed & up until a few days ago, the color was always consistant.  Presently, the color is dark (but not black).  BM's are not uncomfortable, but do cause some cramping in the belly.  Should I be concerned about this since there is a family background of stomach cancer & polyps?

Thanks,