What Causes Redness, Pain And Itching In Anus?

i have redness around my anus, it itchesm and has mild pain with physical activity. if i sit down and relax no problems. it comes and goes never for a certain peroid of time. I do not have anal sex or have any typical stds and dont even go around that area with sex. i work outside all day in good 80-95 degree heat and sweat alot. was just wondering if it can be a sweat rash because i do sweat alot.