I'm Raising A 14 Yo Grandson With Mental Health Problems.

I'm raising a 14 yo grandson with mental health problems. He's been diagnosed with PTSD, depression, non specific mood disorder, intermittent explosive disorder, ODD and impulse disorder. He has been hospitalized 5150 6 times. We have tried so many meds but can't seem to get his explosions under control. He was most recently on a cocktail of Haldol, latuda, Cogentin and with the hope of weaning him off Haldol we have him on Trileptal as well. We recently added a dose of Klonopin but had to suspend that because it was making him angrier! So, I have 2 questions: is lithium something we should try? Or is he being over-medicated at this point? We need help as he's a large teenager (5-10, 220 lbs) and is very aggressive.