Oh, I think it was from a hemorrhoid
bleeding. This is because when you have some constipation
and your waste gets hard
and even enlarged, it will go past those delicate tissues and make them bleed, and it'll show up on toilet paper just as you described. Hemorrhoids come from straining because of constipation, the tissues swell up and will bleed and hurt when hard waste is pushed past them. The three fixes for constipation are: Enough water, enough fiber foods, and regular exercise.