My son keeps cutting himself.

My son has been suffering from Hidradenitis Suppurativa for over 10 years. We have been told that it's very bad. He was in a course of Exemptia injections . Even though it seems to have subsided, he seems to be depressed and has mood swings. He is almost suicidal. He cuts himself with a blade frequently. Not just 1 cut... but several. He says the voices tell him to. There are times that he shouts to someone to shut up but there's no one. When I asked he said the voices won't shut up. He says they tell him hang himself or cut himself. I need help. I have a psychiatrist friend in South Africa who has spoken to him and started him on Nexito 20mg and Clonazeppam 0.5mg. He's been in this for about 3 weeks. The cutting has worsened since being on these tablets. Something which the doctor told us to watch out for. Please help me before he dies something irreversible.