The ones who are in the most pain are the ones who bark the loudest.  Pain has many causes and it manifests in many ways, not always with crying.  It shows up as impatience, frustration, and of course anger.  Be patient with yourself and others when they display pain in its many guises.  Do not condone hurtful behavior, but in understanding its cause, perhaps you can help transmute it to love with your loving compassion.