Injections. When I hear "bad back", it sound like this has been going on for some time. Therefore the number one cause of chronic back pain is arthritis of the lumbar facet joints. Muscle tension/spasm can cause a lot of pain but usually triggered by underlying arthritis. Disc problems can also contribute to certain pain patterns. Talk with your doc about your particular symptom complex to discuss treatment.
Rest and exercise. Rest, over the counter anti-inflammatory medication and structured exercises (http://orthoinfo. Aaos. Org/topic. Cfm? Topic=a00302). If these do not help I suggest seeing your primary care doctor.