I suspect it’s my piriformis muscle, which can get all clenched up and then squeeze the sciatic nerve. It’s painful enough that I couldn’t run Friday—I tried, but it was just too painful. Then Saturday night, returning to bed from a bathroom trip, I smacked the everloving crap out of my upper thigh, same leg of course, on the post of the bed’s footboard. Yeowch that HURT plus the force of the blow made my left hip feel really weird and not in a good way.
Anyway, one way to help relax the piriformis muscle, aside from getting stronger and stretching more (all of which I’m working on), is to roll that part of the bum on a tennis or lacrosse ball. It’s not a pleasant feeling to roll on a ball because basically you’re rolling super tight muscles on a hard object. But I’m willing to spend a few dollars on some tennis balls if it will help. And I doubt it can hurt, or at least not any more than I’m hurting right now.