depression after birth

I had my baby boy 8 days ago and since I've suffered constant anxiety and sadness. The anxiety is so bad my chest hurts. I can't eat, I've already lost 21 pounds l. Before pregnancy I suffered anxiety and I self harmed, and now I'm more depressed than I've ever been. I'm locked inside all day, it's too cold to go outside, my husband works so much and has the car so I can't go anywhere and no one talks to me. I spend my day taking care of my son who I love more than life itself, and when he's sleeping I just cry all day. I don't know what to do anymore