I have a small bump on the outside of my anus. Sometimes it get extremely irritated and itchy, rare spots of blood. What could this be?

External Hemorrhoid. Remember those "preparation h" commercials on tv or radio? Growing up i had no idea what peparation h was for, or that the "h" stood for hemorrhoids! i'm not saying thats what you have - i would have to see the bump to confirm it, but from your description it sounds like an external hemorrhoid.