I had a similar thing happen to me early this year. I started weight lifting and doing sit ups. My back really hurt. My sister is a physical therapist and she said I should rest it until there is no more pain, and when I start, do it gradually.

Have you tried going to chiropractors? Specially the ones who practice Gonstead technique? Search Dr. Ian on youtube, he's based in Australia, and Dr. Rahim who is based in California, so you have an idea of what they do to treat patients. Don't just go to anu chiro who juat cracks your joints.