It seems like there aren't a lot of good answers out there for those of us with TBI. I've taken a few knocks to the head myself for odd and ridiculous reasons (two of which knocked me out), and have never been checked for that.
I've read that docosahexaenoic acid can supposedly help keep inflammation down, so I get some in a liquid that comes in rosemary, unflavored, or lemon It comes in 250ml bottles and costs almost a dollar per day at the amount I take, but for me, for my mental health, it is worth it.
I also get as many fruit and veg as I can, eat oatmeal several times a week, stay away from saturated fats, and take some lecithin granules (for choline), too.
None of this will solve your problem, but the way I feel about my own health is every little bit helps, even if I don't see obvious results right away.