This is a very good question. I’m sure there are many people who can relate. Of course, any traumatizing situation can cause PTSD, but you would need the evaluation from a mental health counselor to determine if that is what is going on for you.
It’s also possible that you are still recovering from a terrible work experience. There is a saying: “People don’t quit jobs, they quit bosses”. It points to the fact that even the most wonderful job in the world can become poisonous if the leader is divisive, unappreciative, disrespectful, and/or disorganized. You experienced the creeping effects of being mistreated over a period of time. It is not at all unusual for people to not understand what is happening for awhile. No one expects to be mistreated. Often the enthusiasm for the job blinds people to the negative interpersonal dynamics — at least at first.
It makes sense to me that you are having trouble trusting that your new situation is any different, or at least different enough. It makes sense to me that you may be over-personalizing comments by your new boss. On the other hand, there may be red flags that your don’t trust yourself enough to heed. Of course you are anxious.
Regardless of whether you meet the criteria for PTSD, you deserve some support and practical help for sorting through the past and for being realistically alert for a situation that isn’t healthy for you. For that reason, I think a few sessions with a mental health counselor or your Employee Assistance Program would be beneficial. I hope you will take yourself seriously and make an appointment soon.
I wish you well.