Suggest Treatment For Back & Hip Pain With Numbness In Knee

for several years I have had pain, some in my lower back, but most of it is in my left hip area and down my left leg, if I stand for longer than 5-10 minutes, my knee will go numb. i've had an mri, nothing was found, arthritis, and scoliosis, and the only offer of any kind of treatment was injection therapy which I can't afford, and have heard rarely works. Any suggestions? I am not able to walk far distances without a period of rest, sitting for a few minutes, then walk a bit further. Really annoying.