Thank you everyone, for your replies.
I did see my dr. yesterday. I've had major depressive disorder for years, and have tried many ADs. I'm also on interferons for MS, and the interferons themselves can cause depression, even in someone without it.
The depression makes me do less, and eat more.
The dr. diagnosed me with bipolar, which is really surprising to me, as I don't have real manic episodes. She wants me to try Geodon.