My back has locked on me in the lumbar region. what do i do to unlock it?

Back pain: Ice/heat, gentle massages, stretches, if these don't help then see Physician.

Depends: If this is muscle spasm, recommend ice to your back to reduce inflammation and spasm and Acetaminophen for pain (I see you take metoprolol and if for high blood pressure would not recommend ibuprofen or naproxen-can increase your blood pressure). If due to mechanical malalaginment (facet joint out) good chiropractor, osteopathic doctor or PT with manipulation training to re-align your facts.