What Causes Pain In Lower Back Radiating Down The Buttocks?

I think I ve injured my back doing exercise. I am in intense pain. The epicenter is my lower back just above the coccyx. However, the pain is shooting down my buttocks, my quads and hamstrings and down to my heels on both legs. My neck aches, my middle back around my spine feels severly bruised and I ve had a throbbing headache. These symptoms have been going on for 4 days, getting worse each day. I ve been taking one Aleve in the morning and one in the evening with little relief. I have not been able to sleep properly for days because of these mostly dull, but strong aches, which are also limiting my mobility. Please advise asap. Thank you. Gabriel