This is called a 'roller coaster ride' for a reason. Possibly you were triggered by something that didn't seem that important at the time.. or your body and brain are just doing what PTSD does to us.. Are you on any medications?
All we can do is assure you that the highs will come back... it is a balancing act that we just stay confused by. I do know that before I was diagnosed... that things would be going good, and then boom , depression... can't say the 'before' was bliss, but it wasn't bad. But I have a chemical imbalance , and was put on antidepressants... so if it doesn't lift soon, it may be something you can talk with your family Dr about. Or if you have a Pdoc, you can have a conversation about this..
It doesn't mean you are doing anything wrong, it just happens at it's own pace.. Sorry you are going thru this.. hope it lifts soon.. Glad you reached out, it's important to know we are not alone during these times.