Thanks for the tip. My research revealed that an organic cause of hallucinogenic symptoms can be Pollegra, cause of which is a nutritional defficiency. Although I doubt that this is the case here, I will give orthomolecular treatment a chance.
Other nutrients recommended in such cases are:
For two months I've been taking B-3 and Omega 3, will add other nutrients soon. I figure it won't hurt, and even if it's not going to eliminate voices, it might help support a healthy brain function, and perhaps repair some damage.