Your question is about a very common problem. Bleeding from the rectum can have several causes, which is why I recommend being evaluated by a doctor
. The source of the blood can be from other areas of your gastrointestinal tract (stomach, intestines, colon), or it can be from your anal area. The location of the bleeding can provide information as to it's possible cause. Given your history of constipation, as well as the pain you feel when having a bowel movement, a problem with our anus is a possible cause. Problems that can cause the type of symptoms you are having include anal fissures, and hemorrhoids.These can be treated with ointments, as well as surgery. Your weight loss is also a concern. Given your weight loss, constipation, and age, you should be evaluated for Inflammatory Bowel Disease (IBD). The two types of IBD include Crohn's disease and Ulcerative Colitis. Also, your bruising and bleeding could be related. Are you taking any medications that may cause you to bleed? I understand that you are embarrassed, but you should have these problems evaluated specifically because they can be related to more serious conditions. I would recommend that you see a gastroenterologist
or a colorectal surgeon
for further evaluation.