I woke up with a sharp shooting pain that starts at the top of my left thigh and shoots down my leg. i haven't done any strenuous activities.

Scaitica: Are you over weight? Abnormal position during sleep or poor quality of Mattress can also trigger this inflammatory process. Try taking Ibuprofen 400 mg 3/day. Apply ICE all day long. There are some stretching Exercise you can do. Simplest is Downward Dog position. IF you loose control of Bladder / Bowel;Go to ER

Various Causes: Radicular pain, or nerve pain or other neuropathic pain manifests as burning, sharp, shooting, electricity-like pain, which can extend to the area along the nerve. Causes her radicular pain can be due to degenerative disc disease, degenerative joint disease, compression at the inguinal ligament (meralgia paresthetica). This can also cause by strain, sprain of the area, or other vascular problem.