What Causes Appetite Loss Along With Pain In Upper Back And Fingers?

I have a bad pain in the upper left hand side of my back. Its sharp and doesn t feel like a muscular ache. I hurts to move to much. I have been getting occasional pins and needles in my fingers and this morning my neck seized up and I couldn t move my head. I am unsure if this is related but over the last 4 weeks I have had a lack of appetite and lost over a stone making my current weight 8st2. I have also have loose stools over the last 3/4 weeks.