That does not mean it is "all in your head" or that it can be cured just by willing it so. But there is a huge connection between the brain and the body that doctors still don't fully understand, and you can indeed die from illnesses that are psychosomatic. Much like fibromyalgia, severe lower back pain mysterious in origin is almost unheard of in developing nations, but it occurs quite frequently in the US and Canada especially among the middle classes. That should tell you something.
For 25 years my brother had terrible lower back pain stemming from an injury in karate, and fear of re-incurring that pain has ruled his life ever since. He has finally these last three years been going to a psychological therapist to deal with his fears of re-incurring that pain, and they've discovered he has had almost no recurrences since he's started therapy.
Not all back pain is psychosomatic (some of it stems from genuine physiological causes, ripped muscles or disc problems), but much of unexplained back problems are. Think about it, and think about reading up on it and/or seeing a therapist to help deal with it. It does not lessen the reality of your pain to seek out a new form of avenue, and it may ultimately help end the pain itself.