PPD at 6 months?

I had my second baby 6 months ago. I had undiagnosed PPD with my first due to a traumatic labor and a baby with torticollis and severe allergies & eczema. It wasnt until the cloud lifted that I realised I must have had it. This time I'm worried I have it, but the feelings are different. I have good days and bad days. Today was very bad as I cried for 12hrs straight and felt like a burden to my family. I also have a constant feeling that everyone is judging me or hates me. I dont know why and I don't know how to shake the feeling. For the first 4months PP I felt happy and okay... is it possible for it to develop at 5-6months? I was diagnosed with fibromyalgia on Friday so I don't know if that might be connected too