Hey.. I Noticed A Soft Bump Near The Anus Area,

Hey.. I noticed a soft bump near the anus area, just outside the opening, closer to the beginning of the anal region .. I never felt anything unless I was in the western toilet and tried to clean my ass with the butt spray. I din feel anything until the water touched the bump. I suddenly jumped out of the closet. The pain was that severe. I don't know what might be the reason for it. And I have no idea how long it has been there. I don't think I get the pain when I try to press it or touch it. But, when the water from the butt spray hits it in force, the pain is severe. What could be the reason? If you could help. Please!!