I didnt poop for 4 days and then in the fifth day i was having bleeding while pooping and ,now its been 7 days but still i am having bleeding not like 7 days ago but a bit blood comes with my poop?

The 13 year old needs to be seen by his doctor to determine the cause of the bleeding-possibilities include hemorrhoids, fissure, etc. His doctor can also treat his constipation to help prevent whatever problem the constipation is causing. He may need to see a GI specialist to diagnose and treat the cause of the constipation/bleeding. Best of luck to you!