pain in the butt

Marathon training is progressing. I've gotten in two 20 milers, and so I guess it's time to start tapering (and by tapering I mean skiing every weekend instead of long runs!). I feel pretty good. Last year, I was incredibly sore for about 4 days after 20 milers. Now, I've got my recovery down to the point where I can work-out the next day. I usually aim for a class at the gym or the elliptical to give my running specific aches and pains a day off. The only thing I'm worried about is this persistent pain. I've had IT band and hip issues before, but this is different. It's not on the side of my hip, it's right smack in the middle of the right side of my butt. I was walking around the house last night holding on to it- which I admit looked pretty strange- and I got some good teasing from the roomies. I've been stretching and foam rolling like a fiend, but nothing seems to reach this particular ache. Not a huge deal, just a pain in the butt!