What Causes Pain In Back Left Side Above Hips?

What organ is located on back left side above hip?I had a small pain starting yesterday morning on my left side and it has turned into a constant pain. No position well alliviate the pain. It''s not the muscle--it's on the inside. I thought maybe kidneys but I have flushed them with water and I have no pain in urination. It seems to be getting worse and I was just curious as to what is located right above my hip on the left back side and what home rememedy you could suggest. I'm not a "go to the doctor" over every little pain, but this is really painful. It's constant.