constipation, flat stools and irregular bowel movements

Im 20 years old, no past medical hx. Family hx of chron's, Maternal uncle.

I go several days without a bowel movement, usually 3-4. sometimes they are hard, some times are mushy and finally some are extremely loose. I have not had any recent blood in the stool, but have had some in the past.  My stools are often somewhat flat but sometimes normal.

Three years ago I had some narrow pencil like stools for about 5 months that went away, I often had a lot of blood with this.

I have had some very intermittent abdominal cramping. They are usually short busts of pain. Occasional occurring just prior to a bowel movement. The pain is usually minimal but have had a few episodes of pain that caused me to bend over in pain.

I am wondering how I am constipated (not going for four days) but then have a very loose BM.

My worry is colon caner, I know it is rare in my age by the narrow stools scare me.

I had a negative upper GI and small bowel study that was unremarkable.

GI wants to do a colonoscopy. Should I have it? Crohn's vs cancer vs IBS?

thoughts, ideas are appreciated.

[Christopher R Watters, MD]

Although cancer would be extremely unlikely colonoscopy is the appropriate next step in your evaluation. There are many other causes that could be determined by the procedure.