Itz kind ov serious but you dont have cancer sweatheart just see a doctor
Geez! All this cancer talk will scare you to death, but you're way too young. Joseph is right that it could be internal Hemorrhoids as those don't normally hurt so you don't even know you have them until they start to bleed, If you don't drink much liquid and tend to get constipated often, that's probably what it is, BUT it could also be a polyp which you also don't feel, but has the possibility of turning cancerous in the long run. Take the time to see the doc and after he rules out the worst, he can advise you on good bowel habits.