Alternating heat and cold compresses. Use each for 15 minutes with a 15 minute break in-between each application. Mild stretch exercise such as touching toes helps.
Latest advice for a dull ache is to keep it moving in gentle exercise because bed rest just stiffens it up. Avoid strenuous exercise. If the pain gets worse, or is sharp or there is tingling or pins and needles anywhere in the body then see a doctor. If it is caused by an accident, then have it checked out.
Soak in warm bath for half an hour. Lie on firm mattress with heating pad beneath painful area.
Simple painkillers, such as aspirin, acetaminophen, or ibuprofen, may also relieve pain.
The main cause of a sore back is inflammation. When inflammation is reduced pain is reduced and generally that will cure the problem. The best anti-inflammatory is zlyflamend. From your health food store.