I would like to help you with your question.
I am sorry that this is happening to your son...and to you.
It might be time to see another provider. You don't say if he has been seen by a physician or a psychiatrist....but it certainly seems appropriate to be getting a second opinion.
The best treatment for depression is medication in combination with therapy. Does he see a therapist? I encourage you to add this to his treatment regime. If you need help finding a therapist, let me know and I will assist you.
Your son has suffered long enough and needs some real relief. Feeling scared by his mood swings is sad...and surely hard for you to see.
I see that you are offline. I will be notified when you come back online and then we can chat.