Tbh, it sounds lot like anxiety and intrusive thoughts. It seems many describe these as "voices" for lack of better description.

But if it's indeed issue of anxieties and intrusive thoughts... find out, before you take him to psych, mention voice and he's on APs.... that will likely not help these issues.

It's not necesarily a psychosis. Try psychosocial intervention first, before you get him labelled and unnecesarilly "treated". Labels will worsen self-loathing by 1000%. And if they are based on misinterpretation of what is really going on... it will do no good.