The inflammation is physiological. The trigger is not physical trauma. It can be physical touch. The trigger causes the remembered physiological response to manifest.

Inflammation is a body defense to trauma. The body responds in expectation of the trigger being real trauma. With people with a history of trauma, either physical or emotional, the body/brain has a hair trigger setting to go into inflammation mode.

Those bumps and jolts cause a startle or similar response that triggers the inflammation.

These sub-concussive impacts do not individually cause inflammation but when they repeat in a small time frame, they can. But, they can individually trigger the inflammatory response in a brain that is overly sensitive to a sensation of head contact.

When I see a person hit their head on TV or in a movie, it triggers a physiological response in my gut and sometimes a headache.

This is sometimes called somatoform disorder. The symptoms are real physiological symptoms.

I struggled miserably with this in the early years. A mild sensation of movement of my head would cause a moment of dizziness and the rest would follow. The more I paid attention to that triggering sensation, the worse it got.
I could not turn my head back and forth when cleaning up after my dogs in the backyard without experiencing this. The little bit of inner ear sensation would magnify. This was worst when I was not getting good quality sleep.

As I said, CBT therapy can help one re-orient the thought response to allow the brain's inflammatory response to calm.

I've seen many here on NT struggle with this for years until they finally sought therapy and maybe even medication to help with anxiety and OCD before they got relief. Then, after months of success, their thought patterns are strong enough that they can stop the medication. When that breakthrough came, they finally realized they were not thinking about every head contact.