I was in the same boat as you are, I'm 21 and have experiencing bleeding after bowel movements since I was 19, I was too embarrassed and scared to have it looked at because it may be cancer. Finally I decided it was necessary to check and it ended up being something as minor as a fissure. I'm not saying that your is or isn't minor but give yourself some peace of mind and get it checked out.
If you want answers, go to the specialist. You are very young to have colon cancer, but bleeding like that should be investigated. Good luck.