I wish I knew more about meds, but it sounds like it could be any number of things.

I have experienced apathy, more so a while back and more recently every once and a while I'll "turn off emotionally" but only for a short period of time. I remember that when I was apathetic for several days in a row I was MAJORLY repressing things. So I know it can be caused by repressed feelings.

As far as medications go, I think you should definitely look into it, because it sounds like you might be on to something. Can you make an appointment with your PDoc?