I fell to the ground concrete bumped my head and fell onto my left side. I blacked out momentarily. Now I have a constant pain down my left arm and at the top of my spine.?

This sounds like you have a pinched nerve. You should try some stretching exercises to release it. If you have no success with this, or the pain is too great, you should try a chiropractor. Otherwise, an acupuncturist will be able to stop the pain, and stop the misfiring nerve.