A serious question

There is a young lady I work with. Maybe 24-25 years old. She just had a baby 4 months ago and I'm worried about her. I'm worried she is going threw PPD and I'm not sure what to do. We are housekeepers and work in pairs of 2. She is my partner and no matter what I talk about she will not carry on a conversation. Not even about her little boy. Anytime I look at her she just looks so miserable and her eyes just look so empty. Today she just started crying out of no where and told our boss she had to go home just 10mins after starting work. I'm worried about her. And I don't know what I can do to try and help her. Any advice ladies? There are more things that has happened or that she does that make me think PPD I just didnt want to make this post super long.