No, auditory hallucinations (voices) are NOT a part of PANDAS. Those are in a very different part of the brain. (I'm a child mental health therapist, just so you know my credibility.) It sounds like he's having some very significant symptoms that need to be assessed by a psychiatrist quickly. Especially if he starts having what's called "command hallucinations," where he hears a voice or voices that tell him to hurt himself or others. Those can be very dangerous, so don't mess around with that. It's obvious something's wrong with his chemistry, which is what's causing this.
Is he on any medication that may be causing this? If not, is there a family history of Bipolar Disorder (used to be called Manic Depression), Schizophrenia, or Schizo-affective Disorder (mood and psychosis issues)? It sounds like he is pretty sensitive in some areas, which is why he's showing many different signs that aren't in one category (OCD, tics, hallucinations, "dark side" = does this mean depression?). Is his sleeping pattern irregular? If so, that may point more towards Bipolar, especially with the behavioral symptoms, hallucinations and ups and downs. Poor guy... just get him evaluated and tell them everything- they will figure it out.
You may want to Google "Bipolar in Children" and see what you can find- the symptoms in children can look very different than the ones in adults. If it's that, he will need medication to stabilize his moods. If it's not, then you at least ruled that out. Act quickly though... poor angel is suffering. Good luck~
Laurie