Take a few moments and check out the fibromyalgia forum. It sounds like you could have that. I go through a lot of those symptoms. And fibro does cause depression. You have wonderful days, not pain free, but good. Then all of a sudden you have very painful days with a lot of fatigue. This could be something to mention to your doctor. There is a thread called fibromyalgia 101. That covers a lot of the symptoms. You could get some kind of idea as to if that is your problem. Some doctors don't believe in it, but many do.
This is just my opinion, but I think that you should check out the forum. Let us know what you think.
I wish you well