I have to back up a PP that mentioned post partum depression. I know there is such a stigma associated with it but if you do have it, getting help will make SO MUCH difference! I didn't want to acknowledge it in myself and didn't get help after DS1 until a friend was kind enough to tell me that she had gone through it and that it's ok to have it and need help! After I found that out, and with DHs prompting, I was able to get the help I needed without thinking that I was an awful mom bc I had it. And you don't have to have all of the symptoms or even the "normal" symptoms to have it!
All that said, it could just be the transition, and yes it is hard! I didn't have any mom groups I belonged to when DS1 was born so I would go to the local coffee shop, get a drink, pick up a magazine, and people watch for a while. It does do wonders to just get out of the house!
Sending hugs mama! This stage is rough but it does get better!!!!