Rectal Pressure

I’m a 38 year old female and from time to time over the past 12 years I will have blood in my stools. Sometimes I will go for months without any blood and then have one bowel movement with blood. Last year in March 2009, I noticed a change in my stools and had more blood than usual so I made an appointment. They did a quick stool test on me and found no blood in my stool. Because I wasn’t haven’t any pain and no blood was found in my fecal test, my doctor didn’t think I needed a Colonoscopy, but if the condition got worse we would do it. Well my stool got better and I didn’t have any blood in my stool until this past February and again it would be with one bowel movement and the rest would be normal. Then last week I had a painful bowel movement and some blood, but again it was just with one bowel movement. Now since this past Thursday, I’ve been experiencing pressure in my rectal area, cramps and bloating, but no blood in my stools. I will be making an appointment with my dr., but I’m so worried about cancer, I’m absolutely terrified. I have two small children ages 4 and 2. My mom had pre-cancerous polyps about 10 years ago and my great grandmother died of colon cancer in her 90’s. I keep reading that only in the advance stages of colon cancer will there be any symptoms.