The anxiety disorder you were living with prior to the injury is probably the biggest factor in causing you to develop PCS. I experienced panic attacks and was dealing with various kinds of low level mental 'wrongness' before my concussion a year ago and I was so struck with anxiety for the months after it that i couldn't do anything. I lost everything. My most distressing symptom was depersonalization (and derealization). But I got better and you will too I'm sure. The knock on the head has sent your brain a bit haywire and stirred up all the bad things that it was perhaps keeping at bay....it's not damaged or faulty....and you'll be ok once you work your way through.