hi, loss of balance is generally due to vestibular disease. Acute onset of this supports a derangement in vestibular function that is commonly seen in viral infections, middle ear disease etc. some drugs that you are using like nucynta can also cause this as a side effect. Rarely, an infarct or a tumor in posterior brain (cerebellum) can also cause this when, it will be unresponsive to drugs. you may try a short course of labrynthine drugs like betahistine or cinnarizine. If you have persisting symptoms, consult a neurologist. hope this helped.