Let me suggest what is happening.
The anesthesia mess you up for a while leaving you with some dizziness. You focused on the dizziness and basically memorized the sensation of dizziness. Stress would make this memorized sensation manifestation more intense so it may come and go.

Now, as the ups and downs of your days and weeks impact you, any of your past or even current symptoms get triggered to be worse.

One of the problems with PCS for a person who struggles with anxiety is sensations that occurred before the concussion that were tolerated without a big anxiety response can become big triggers of anxiety.

An example would be. Before PCS, one may occasionally feel dizzy from getting up from a chair quickly but resolve that dizziness and move on without a concern. After a concussion and dizziness related to the concussion, any time that 'got up from a chair too quickly dizziness' manifest, it become a major issue and anxiety trigger thinking it is PCS that will never end.