Is An Itchy, Brown Lump On The Top Of Anus A Cause For Concern?

Hi I have a brown lump right on the top of my buttcrack. It sometimes itches it doesn t hurt. Sometimes it s scappy. I don t know what it is and the first time I noticed it was when I fell and hit around that area at first it hurt but now it doesnt.. What could this be I am scared its something serious.