I Have Been Using My Rowing Machine A Lot (45

I have been using My rowing machine a lot (45 min to 1-1/2 hours nearly every day), and I've noticed that my butt gets sore as I row. In checking it, I found that the skin between my buttcheeks has turned a bluish color, and there seems to be a very slight raised edge at some areas along the perimeter. It only hurts when I'm rowing, but it can be a bit uncomfortable when sitting. When I row, i wear polyester/spandex underwear and baggy gym shorts, and I sweat profusely.