Omg Bleeding What is this?

well i am 14 and well i had my galbladder removed about 2-3years ago and have had lots of adominal pain sense i have irregular periods from pcos and well i just dont know what this is but im having very bad cramps and well im bleeding from my rectum what could this be is this serious i dont want to wake my parents up but is this something to worry about? bright red blood