Unless you have disc issues, may not be your back...I "tweak" my back a lot. Pain is always lower middle. It is never my back. It is combo of tightness in hammies, IT Band, gluteus medius, gluteus minimus & obliques...
Ice and rest for a couple of days to allow swelling to subside then pigeon, half-seated ankle to knee, full seated ankle-knee, pyramid and other hammie stretches, and IT band stretches 2-3 times a day for 3 days with no other activity...then see how it feels...with that routine, mine goes away in 5-6 days total..