I WISH I KNEW WHAT THIS WAS

There's an area of skin on my right arm (basically where the tricep is) that's weirdly sensitive to the touch today. It doesn't seem discolored or in any way visually unusual; it doesn't even really hurt when touched, it's just kind of ... bothersome. Anyone know what I'm talkin' 'bout here? Or is my body pioneering new ways to be annoying?