Common causes of low back pain are- Poor postural habits Muscular strain Ligaments sprain Herniated disc Spinal stenosis Osteoporosis Fibromyalgia To allow me to help you better, please let me know if you also have any of the following complaints: - Pain radiating to lower limbs - Parasthesia and numbness in lower limb - Weakness in lower limbs - Back pain develops after lifting heavy weight or strenuous activity - Pain associated with stiffness in your back - Pain aggravated on forward bending - Pain in other joints from you question it seems to be muscular in origin.I advise muscle relaxants like cyclobenzaprine, NSAIDs like aceclofenac or tramadol and neurotropic drugs.I send them for muscle strengthening exercises and Physiotherapy along with this.Loosing of excessive weight if you are obese also helps in relieving symptoms. Take vit D also if you hardly go out in sun. Consult a pain physician or orthopedecian for further advice