I may have done injured myself overloading on a back exercise, and that was months ago, I have soreness every now and then in sports, and lately when sitting down I can feel weak/sore where my tailbone is (weak from being inactive lately?)

the main problem is when straightening my spine, movement is jagged and not smooth, going into detail I feel this more when using my back muscles to straighten, and lately when I do deadlifts (works back muscles) I seem to feel better temporarily and the feelings is almost gone

(the discomfort is 'directly' above my buttocks and seems to be slightly left of the spine)

i wonder mostly why my spine moves in a jagged pattern if anyone has thoughts on this please say so