My cousin has Down syndrome, but I am concerned that he may be diagnosed with more. he stopped talking completely and has never said a word since his childhood. He is constantly in a hallucination state. He's constantly talking to himself, and making expressions, like he's either scared, surprised, and sometimes really happy. Sometimes it seems as if he's talking to someone around him. He also goes into our living room often and vigorously shakes his whole body for almost hours in the same spot