I have horrible pain along my right leg?

I am a 24 yr old female. I have horrible pain along my right leg. The pain starts at my lower back and goes along the back of my right leg. My leg hurts badly when I sit for long or stand for long. I feel better when I walk. I am also unable to sleep on my right side because this will cause my right leg to pain horribly. I also have pain along my right hand, starting from my neck, along my right shoulder, back, right breast, right hand and fingers. Please help me. Sometimes I feel as I am going to faint because of the leg pain.