you poor chook.
Sometimes I find that the best thing for me to do is just get out of the house for while. Even in awful weather I just rug us all up and head out to a shopping center with a play-space (or a play-cener if I'm feeling rich).
Have you had a chat with your MCHN? When one of my friends had PND and was pregnant with number 2 her nurse got her daughter a place in a childacre center one day a week that was subsidised by the government.