I can't really say what is happening to you but I would guess that you probably have a lot of unresolved feelings about your previous therapist and the termination. I'm not sure what the circumstances were but I know termination is always difficult regardless of whether we are "ready" or not.

Have you spoken to your current T about how you're feeling? I think it would be good if you spoke to them about all the things you have written about here and get the support that you need. I think it is very normal for our mental health to worsen in times of stress; our journey is not linear and this is not the end. I hope you feel better soon.