You are a great catmom! I had the same experience with my RB kitty Casey (RB, 2002). He was on anti-depressants because of one of the other male cats in my house. He was never the same while on the meds. I finally decided to take him off of them and re-home the other male (Casey was with me far longer than Tucker). It was the best decision I ever made!! Tucker got a wonderful furrrrever home with some friends of mine and Casey was back to his old self.

Go with your instincts. Unless your cat NEEDS the medicine for say Diabetes or Seizures or some life threatening illness, it's obvious he's better off without them.