I just posted this comment on Amanda's blog.
It may be helpful so I think I'll post it here also:
You're not alone. Depression is scary and tough to explain. As long as you do not or have not contemplated suicide, have faith--no one stays depressed forever.
I can distinctly remember specific and seemingly insignificant events that shook me out of depression from 30 years ago when we hired a salesman whom I hated and I needed energy just to fight him, to recently, when I got a new phone and stayed up all night for two nights to figure it out. In between, there have been many other events, but none related to making a lot of money or losing it, or walking the beach for hours on end because my husband was trying to help, or getting a new dog or cat or bird. We all know that money and physical beauty don’t prevent depression--think Catherine Zeta Jones--and she even won an academy award.
I have some of my own theories: depression is caused by chemicals in the brain, many or even most really creative people go through bouts of depression, there may be some connection with the chemical changes that cause migraine, depression is hereditary, and something happens that instantly changes you mood: you can undoubtedly remember each moment when you started to descend.
Hopefully, you have been trying a variety of meds along with all the other methods. Here are some more: sniff oil of peppermint to ward off migraine and anxiety, take deep breaths while you count backward from 300 by 3's, run, walk, or race around the block until you are exhausted, and, most important of all, don't be embarrassed to admit to and talk about your depression.
In life s--t happens and bad things happen to good people.