I think how you present yourself can make a big difference.

I felt like because I didn't understand it and most other people didn't understand it and the actual incident which caused the injury didn't sound particularly serious, I had to be apologetic about my symptoms. I would tend to waffle, give a confusing list of symptoms and say things like "well I hit my head in March and since then things have been all weird". Looking back it's no wonder people didn't know what to make of it.

When I got more informed and familiar with this condition I also got more confident in expressing myself and the seriousness of what has happened, without feeling that I have to justify myself or apologise. I now just say "I have a brain injury". You won't find anyone who doesn't take it seriously if you tell them that.

It's also useful to have a speech prepared which succinctly and accurately describes your major symptoms. Devising a new explanation each time someone asks what your symptoms are is one of the most challenging cognitive tasks I have come across, which meant I didn't express myself well early on.

That said, there are people who have had every opportunity to understand, and don't seem to have made the effort. There are also a few friends, and one in particular, who have really come through for me. I consider this revelation of who really cares about me and who I shouldn't waste my time with to be a major silver lining to this whole experience.