I have a pain in my lower back it isn't a aching or throbbing pain but possibly a nerve. anyone know of this?

I have a horrible pain in my lower back. It isn't constant only when I try to bend over of sometimes when I walk it gets unbearable. It's only in the center (like spine area) and I'm guessing maybe its a nerve. I have gone to my family doctor and she just gave me medicine for inflammation and well it doesn't make it feel any better I have also gone to a chiropractor but that didn't help either. Does or has anyone ever had this problem or does anyone have any suggestions?