I have a difficulty passing stool also my stool is sometimes very soft and small..or like very thin..if i pass large stool it pains..i have 3 bumps inside my anus..in the anal canal..is it anal cancer..i m only 20 years old?

Get a medical checku: I suggest that you have a check up by your physician who can do a good examination of the anal canal using his/her finger and anoscopy. If there is a suspected mass, an ultrasound examination can further demonstrate the nature of this mass. Your age is on the younger side but Cancer does occur at younger ages although it would be uncommon in your age range.