Long Lasting Back pain?

Patient: I have been to three doctors, a chiropractor, a physio as well as having two clean blood tests, multiple xrays and a ct scan. Every person I have seen said there is nothing that they can see that is causing the pain. All they know is that my muscles are that tight it feels like bricks and nothing is loosening them. No injury or anything that couldve happened to cause anything. Just happened out of the blue and has stayed for 8 months now and is getting worse.

Symptoms: Throbbing back pain, fatigue