Blood Coming From Bottom After Going To The Toilet And

blood coming from bottom after going to the toilet and dont know what to do about it. I have been suffering constipation and am unsure if its linked with that. I also had a pain in my side about 3 days ago but that cleared up by tself. I was worried if it was a serious problem or just because of constipation? I am a 15 year old female with no medical history and am currently on no medication