Red in stool is it something seriouse?

well im on pms and ive had all the pms symptoms and i think im close to getting my period but idk when im suppose to get it and so i thought maybe my poop had some red in it cuz maybe my period to come got mixed in it oh and the blood was brick red so idk what could it be? oh and yesterday i punched my stomach cuz it was doing annoying flips cuz of a reason im not telling you but it was bareley like a pat it didnt hurt ive been punched worse oh and im 13 plz help im like crying right now im soo worried :'(