Are you wiping yourself after you poop? Oh wait...it'd be brown if you forgot to do that.
Seriously, get some prep H ointment (not the gel) and use it for a week 3 times a day. If it doesn't feel better after that you should see the doc. Your ass isn't something you want hurting unless it's getting fucked.
Lay off the Dave's Special Sauce. Should help. down, down down into a ring of fire....
seriously, get some Preparation H, and if that doesn't work, go to the doc, in case you ahve some kinda infection. I realise a "pain in the ass" sounds funny but I bet it ain't funny when it happens to you....