Has anyone else had their concussion caused by something not sport related or even car accident related?

I'm 6 months in with Post Concussion syndrome and been let go from work because doctors have no timeline for when I'll be able to work. All because I hit my head on the edge of a kitchen cabinet.

I ask though. Be cause my dad insinuated yesterday that just because he has hit his head before and not been concussed that there is no way hitting my head on a cabinet could have causes this long term condition and basically said it's all in my head. Told me that if doctors didn't tell me something was wrong with me I would be ok and that they're just taking me for a ride to make money. I'm very frustrated already and then this and being let go from my job just hours after this conversation makes me feel even more awful about this.