I have multiple chronic illnesses, including Interstitial Cystitis and Bacterial Overgrowth Syndrome in my Intestines. I've needed to take pain medication for some of my other conditions, but this morning I found quite a lot of (what appeared to be) blood in my stool. I've tried hard to regulate my diet in order to combat the side effect of constipation (from the pain medication) and usually do well. (I use a combination of bran cereal, flax seed, vegetables and fruit, as well as senna. I realize I need to see my doctor, but wanted to know if there are multiple reasons for this particular symptom.