My dr failed to warn me to be careful of ANY head impact after six concussions, so in the next 2 years I hit my head twice and noticed dramatic increase of symptoms, since then ANY hit to my head causes increase of symptoms. It is the brain impacting the scull that causes the damage. It could be that the area of previous damage is very sensitive and that you need to be more cautious of any impact. Like when you get a bruise or cut, even the slightest touch can cause pain. I'm not saying definitively that an impact with a pillow can cause increased symptoms, just that, in my oh so humble opinion, that we need to be mindful of the delicate nature of our condition.
That being said, I still ride motorcycles. duh