If you are feeling apprehensive and delaying it, you should know that getting a colonoscopy is a painless experience. In and out in a few hours.
My mother had one done when I was a kid. I only remember her being absolutely humiliated by the "air" on the trip home - as children we couldn't not giggle about that particular after-effect. Even back then it was an out-patient ordeal. She did say it was like going to the dentist - scary but otherwise a breeze! (her pun, not mine...)