A person will bend a certain way with little problems for years. The backaches that you get from time to time are giving you a warning signal. With a more severe problem, the pain is more intense and refers further into your leg. The sciatic nerve travels from your lumbar spine and down the back of your leg. Many people do not experience pain or numbness along the entire path of the nerve, but rather just one portion.
Some people just have symptoms at the foot, knee or buttocks.
The location of pain is dependent on how the disc is placing pressure on the nerve at your spine. Many back injuries due to disc bulges are managed non-surgically. Exercises can help to reduce the stress on the nerve by providing stability and an equal distribution of forces through your spine. Consult multiple professionals prior to making any decisions to have surgery or not. Consult a physician.