I cant take the pain anymore please someone help?

I'm 16 years old, iv nvr had ual through my (idnt know if this is relevent) but i'v had this really bad pain in my hole for nearly 3 months now its like a gl cutting through it whilst i poo ....and thers blood there aswell, i dont know wot to do iv been avoiding going to the toillete and it really hurts when i poo, i just do not know how it started it began to get worse and i cant take it any longer please advise me im only 16 im too scared to tell anyone