What Causes Pain In The Feet And Legs?

I m a 51 year old female. I ve been in pain since before Oct. of 2013. The pain is mostly in my feet and legs. Sometimes in my hands and neck. I ve had X-rays, nerve conduction test, MRI of head, neck and back. Nothing showed in head and neck. Back showed L4 L5 S1 buldging with two vertebrae turned possible pinched nerve? Ive been checked by family doctor, neurologist, spine ortho doctor, podiatrist, psychiatrist, had labs of every kind. No one seems to no where this pain is coming from? Like I said it s mainly my feet and legs. It doesn t radiate, it just throbs, the tops of my feet are painful. I now have &700.00 shoes that aren t helping me at all. Do you have any idea? Am I nuts? When do I stop going to doctors? I m on lyrica now with some relief. Started two weeks ago.