How to relieve back pain..?

I have a track meet tomorrow but my lower left back is kind of hurting. I mean, it's not hurting to the point where I should sit out of the meet tomorrow, but I was just wondering if anyone knows how to relieve it..? Do I ice it, rub it, take pain reliever, do stretches?? I already took a couple of Ibuprofin. Also, does anyone know stretches for the back? I really want to make sure my back is feeling better for tomorrow.