A piece of foam 2 foot long Daz will change you’re life m8,lower back problems more often than not come from tight hamstrings,hamstrings go in to you’re glutes and lower back putting a strain especially on you’re back.
You can also get policeman’s foot or planter tightness in the foot, it all comes from tightness in the hamstrings.
Roll the foam on the outside of your thighs too up and down what’s called the T band it also frees up lower back.