Bell’s Palsy is usually related to an injury to a cranial nerve.  If you can’t identify a source of the injury, chances are it was fairly minor and should improve by itself fairly quickly.  There is a correlation between immune system weakness and recurrence, so trying some alpha training at P4 or O1 might be a good way to work with it.  It won’t likely change the nerve regeneration rate, but it may help one feel more relaxed while that’s happening, help the immune function and generally feel good.  None of that is bad.