rectal bleeding?

my friend is a 21 years old healthy female. the first time she noticed blood in the stool was about 5 months ago. the color of the blood was dark red. and appeared in the stool for three times in a row. She didnt suffer from the rectal bleeding again until this month. the first time there was large amount of dark red blood. second time was about a week after the first time, however the amount of blood was far less than the first time but same color. all the episodes of rectal bleeding were with no pain. no complains of constipation or diarrhea. Thank you appreciate your help.
There is no history of colon cancer in the family. however her grandmother was diagnosed with cancer in her 60s. and a cousin was diagnosed with thyroid cancer in her 20s.