[davidr3]

Listen to floridaorange he knows what he's talking about. Usually it's the piriformis, even more so if you don't exactly have back issues. There's always the possibility of compression though. Strengthen your abs, and back. Stretch out glutes, including the piriformis, lower back, core, and for good measure i'd work on your hips too. Instabilities can really throw you out of wack.

[Kooch]

As others have said. Piriformis, iliopsoas, and glute med. keep those stretched and strong. kegel exercises can help as well for general muscle imbalance in the lower back and core. I rowed competitively in college and had back issues along the way. Ended up with a herniation years later (due to improper clean and jerk set) with bad sciatica that required surgery but that resolved it. I have now been practicing martial arts for some years and have had a recent bout with sciatica that was related to glute med issues from kicking. Easy to think the worse when things like that happen but unless you have had serious trauma i have found it's generally related to something being tight and/or weak. Be patient and keep searching and you will be fine.

[Cajun1]

Three week update: The piriformis seems to be the culprit and while the roller and ball can be uncomfortable to use, they are effective. Once again the Bimmerpost community has been a tremendous help. Thanks guys!!