Synthetic cannabinoids (aka Spice, K2, etc.) are unlikely as the effects generally peak 2-3 minutes after smoking and the user is back at baseline within an hour. Long term usage has resulted in drug-induced psychosis in a small number of people, however.
I would put my money on mephedrone (aka Bath Salts) as the culprit. This substance has been known to cause psychosis similar to what you describe after just one use.
Long term use of methamphetamine, cocaine, or other strong stimulants can cause this as well.
Obviously, all guesses in this thread are just that - guesses. A full drug panel conducted by the hospital is the only way to find out what, if anything, is in his system.
I hope he recovers and you find some peace. Good luck.