If this is something to do with a trapped nerve or a spinal issue, maybe a chiropractor could help you out? They can manipulate your spine a bit and maybe free something up.
Or perhaps a physio if they can x ray your spine and see if there is anything odd going on? I had dreadful sciatica for a while (pain and numbness in my lower back and right down my left leg and foot) and a few sessions of physio sorted it right out.
Good luck.