Good for you for getting it together again and taking control. Congrats on a whole month! Well done.
I'm sorry you're feeling sad, but see it for what it is... you will have your up and down days. Your brain is trying so hard to adjust to what it's been through and trying to return to a state of homeostasis.
Lots of things are going on in your body while it's trying to heal.
I found that reading about it and being able to put my finger on why I was feeling a certain way, helped me a lot to get through it.
Good luck and keep posting.