Hi mitch. Do you notice any blood on your toliet paper or in the stool? It could be hemmeroids. I know when I sit on a hard surface for any length of time, mine will act up. It usually feels like I am passing knives, especially if I have to strain for a bm, and I usually get some bright red blood on the t.p. maybe a little in the stool as well. It usually stops within a day or two. If you are very concerned call your doc.