When I was on Zyprexa I felt like that. It wasn't like a mute flat it was more like an angry kind of flat though I never expressed anger, it just felt like I was frustrated the entire time. I couldn't really express it or feel anything else. It was just strange.
They added Welbutrin and my mood became even more unstable and strange. I just stopped taking meds for awhile. Then they tried to put me on Abilify and I had a very bad muscle reaction. Haven't taken meds since. I just got sick of dealing with that game.