Go to a doctor i could tell you it could be this or it could be that, but i would only be guessing. A doctor may be at a loss to tell you what it is also, but after some x rays, or even better an MRI, certain things could be ruled in or out, and you would have a clearer picture, and some of us may be able to give you some useful advise. Getting rid of back pain is not as simple as going to a doctor, and getting a diagnosis, and receiving a treatment that makes it better, i think you probably know this, you have to persevere. One thing i would say is if conventional doctors cant find something wrong with you chiropractic is worth considering, but as with any kind of medical practitioner make sure they are good.
All the best starangel