| Hopefully this is just a hormonal blip that will get better soon, but if it worsens do see someone. Know that you're not alone, and depression is very treatable. I suffer from clinical depression and a prescription for an SSRI (anti-depressant) from my wonderful GP meant all the difference in the world for me.
Try to focus on things that make you feel good, if at all possible. Treat yourself to a warm bubble bath, ask your hubby for support (and maybe a massage!), talk to a friend on the phone, play with a pet -- anything that makes you feel at peace will help. My doc recommends walks, especially if the sun is shining; she says there's a real connection between mood and exposure to sunlight.
Low thyroid hormone can also bring on feelings of sadness and depression, and it's often overlooked. If you were borderline-low before you got pregnant, your levels may be lower now. If you've got other symptoms of low thyroid (feeling cold, easy weight gain, coarse hair/skin, tiredness/sluggishness), ask for a TSH level blood test from the doc. When my doc raised my prescription, my mood improved perceptibly, within a week or so.
I hope you feel better soon *hug* | 
