My a nus/rectum area hurts?

I have been constipated about 3 times in the last 2-3 months. i have been taking metamucil for fiber. recently, i have been constipated again and this time, i am experiencing pain around my , it feels like its from te inside. when i try to poop, it doesnt hurt so i am not sure what is causing this pain. i cant go out to do anything or any activities because if i walk, it starts hurting.