A few weeks ago, I was doing adductor flies to strengthen my inner thighs. I hadn't done the exercise in awhile and I didn't stretch afterwards. The next day I felt a tightness in my groin (specifically, up and to the left of my scrotum). It's not painful -- feels like a pull; and it doesn't bother me all the time, but it is sore when I get out of bed. Is this a sports hernia or a muscle pull?