Strong backpain from unknown origin

Hello! I need your help, please. I'm a 35 yrs old woman. I have very strong backpain for about four years. In the beginning, it was the worst. I could not sleep, just about 3 or 4 hours per night, then I woke up to a very strong pain. I needed to stand up, and moving my back, but could do it just slowly, motions was very painful. It needed time (about half an hour, or sometimes an hour), while I could stand straight and walk and move normally. While I was sleeping, I just turned from one side to the other. The pain is typically in the middle of my back, sometimes lower, too. Sometimes there are pain in my fingers, too. Very hot shower ameliorates, can more easily moving. Doctors found nothing. I don't know, what to do. I had sporty and active life, did exercises, have a healthy lifestyle, I am not weak. Now it is a little bit better, but not good at all. I must get better, because I'm on my own, and there are no help, must work to get paid.
I thought Phosphoric Acidum maybe can be good. I do not like carbonated soft drinks and similar things, but sometimes, especially if I feel tired, I feel like I MUST drink it (but not cola or energy drinks, just Fanta or ginger), and needing fruits, fruit juices, sour and carbonated drinks to get better. I am chilly, I like hot showers and hot weather. Massage is a very important thing for me, I like it very much from my early childhood. It is like something that keeps me going, keeps alive. :)
I have a memory, that in that time when this problem started, I had taken ananas-papaya enzyme capsules, for a couple weeks. (A naturopath told me she thinks it will be good for stomach "bubbling".) That thing is an acidy thing, could it causes my problem, what do you think...?