Chronic Middle Back Pain

Patient: I have had back pain for years. It is my middle back and goes up into my neck and shoulders. It feels like it is my muscles. It doesn’t feel like it’s coming from my bones. When I stretch it feels good, but it doesn’t really help. I’ve been looked at for fibromialgia, but don’t have that. I take over the counter pain killers every day for it. It doesn’t matter if I do nothing all day or am active all day, it still always hurts. I am mid 20’s female, no children, and I have never been injured in anyway. Any suggestions on what could cause this kind of unexplainable pain?