Go to your doctor and ask for a physio consult at a therapist near you if you really need to know a specific place of your lower back pain. The exercises are common for the whole lower back, you can find some when googling with "mobility exercises lower back". Success solving your problems. BTW upper back problems can also be solved with the right exercises, upper back problems also often can cause intestine and other problems like stomach, kidney and liver. Nerves have 2 main functions, steering all parts of your body and feedback to the brain.