I Went To The Bathroom To Urinate This Evening And,

I went to the bathroom to urinate this evening and, afterwards, noticed blood in the toilet and on toilet paper. I realized it was coming from my anus. I had no pain, have no pain, no muscle cramping or abdominal pain; no constipation, or diarrhea, or hemorrhoids. I am a type 2 diabetic who takes both insulin and metformin. Could the metformin, which (after the first couple of months) gives me no GI problems, be the cause? I'm 33 years old, I was diagnosed diabetic 5 years ago, I have hypothyroidism, polycycstic ovarian syndrome, and lupus. I take 112 mcg synthroid, 1000 mg metformin, and 25 units of a 12 hour slow release insulin. Could any of my medications, coupled with stress and/or depression, cause rectal bleeding and should I see my doctor even if I don't notice any further bleeding?