my son hears voices in his head

It all depends on how your son takes and experiences these voices. Can he cope with the things the voices are saying or does he mind the whole thing happening? The reason I ask this is because the recent studies determined that hearing voices may be normal and that one in 25 people hear voices and many of them don’t do anything about it as they don’t have problems with the voices. It is also said that those people who have other problems and who are going through rough times will not cope very well with hearing voices while those who feel well generally don’t have problems with their voices and often find them inspiring.

Previously, hearing voices was linked to schizophrenia, bipolar and other psychosis but today hearing voices can be looked at something different like homosexuality.

This may come as a surprise to you but these are relatively new findings.
You should talk to your son about his experience with the voices, talk to him if he could manage and control them and learn to live with them. I reckon that this way is much better than having to take all the psychic drugs when he is already taking some heavy stuff for ADHD.

He should see a psychiatrist no question asked to determine if another disease may not be developing according to his other symptoms. But before you do, talk to him about the voices and see how he sees them.

so,non of you and his father are system members and know what is happening!!