Pain in left leg. Doc she need to visit?

My mother is suffering from a sever pain In left leg. Actually its backpain which is radiating from back to legs. Its causing severe pain in back, left buttock area and a pressure and stress on the nerves of left leg. Nowdays She is getting treatment from a homeopathic doc but I have certain doubts about the pain as the doc is not providing any such details about it(also its continuously paining even after taking medicine). The doc said that its cervical pain. But as per my knowledge cervical causes pain in head or neck and shoulders area. I googled about the pain and found "Sciatica Pain". I wonder is she suffering from Sciatica pain? If so what can be the reasons of this pain and which doc she need to visit? Or may be she is suffering from something else. Need consultation please