I know exercise in general is supposed to help, however...

Back when I ran distance, my mood swings were incredibly less severe and I was told it was because running really heightens those chemicals and brain processes. I can't physically run anymore and ever since, I've found that my moods just get worse and worse. That runners' high seemed to have at least worked fairly well for me. Just a suggestion, but if you can, get out and jog. It's not as boring as one might think if you take along some music