Going through the same thing myself, and its pretty bad. I've have minor episodes of depression at times in my life, but this is weird -- comes on suddenly with no obvious trigger, and lifts pretty suddenly as well, and it is a severe depression while it lasts. Kind of like bipolar without the manic part. Just seesawing between normal and several depressed, sometimes several times over the course of a day!

Lately the depression has been getting worse and lasting longer, so I think it is time to see a doctor about it. Hoping something will help. This is no way to live!