Stepping or walking will not damage your brain. Something mild like walking or turning/shaking your head that causes a return of symptoms is not causing damage. If you smash your thumb, while it is healing, it will still feel tender to the touch, even a very light touch that could never cause any damage. It is the same with your brain.

A neck issue can easily be the trigger.

I think you are correct at pointing toward your intense OCD/anxiety. That can make a symptom that would normally be a 1 out on a 10 scale appear to be a 8 out on 10 scale.

What are you doing for your OCD? OCD makes PCS miserable.