Before you go "medicating" him, try Feliway. It works, trust me!! I have 7 cats in my house and it works like a charm. Get the Concentrated spray, not the plug in diffuser, as the spray works instantly.

I hope he comes around. He obviously has bonded with you. Just like Bad @$$ Buddy bonded with me. That's why I got him back. He and I are in sync with each other.

Good luck. Please try the Feliway first. I had a former cat medicated once and he totally changed. He hid all the time and was very cranky. Turned out another cat I had was bullying him. That cat, Tucker, is now living with my friends in Colorado.