Poison screenings are not typically in regular blood work panels.
Usually doctors have to add that order in.

Neuropathy for me started when I took a hard shock up right side in a car wreck. I started having a burning pathway from knee to hip about three days later. There was nothing to have surgery on as my MRI and Mylogram were fine. Since then, lumbar,knee,hip, and buttocks have all had their turn as being the most painful. The bone bruised nerve(s) that may be your situation was maybe the same for me. If you read and learn to do searches, you will become more familiar w/the symptoms and perhaps what to expect. I do not wish this affliction on anybody. I read of your pain, and in the lumbar also, it made it hard to ride in a car for sure. You will travel your own road, but I must say that I had to get pain relief from the Dr. Only then did my life get better. You might search "Trauma Induced" or "Double-Crush Syndrome". As I close, a rehabilitaion trained deep tissue massage therapist and the aforementioned TENS unit helped me get through the beginning. Good Luck, Ken in Texas