For years I started getting this fluid buildup in my ears. At best, I felt occasionally dizzy. At worst, it felt like my brain was in constant "I feel like I have a cold and I'm so slow to think".
Short story: I've drastically reduced carb intake (letting myself cheat a little on Sat.) and definitely no alcohol. The effect has been amazing. I feel 10-15 years younger. My brain is back. Fluid's gone. So many other body things have improved: no joint pain, no weird rashes. I used to get these awful colds, but if I've had a cold this year, I can't even remember, it must have have been tiny.
It's wild how many folks now who I talk to who have similar symptoms and never try to simply cut out the damn carbs and watch as they eat tons of sugar and alcohol. It's really worth a try giving those up for a week and see how you feel.
I've written about this before on HN so won't rehash everything (https://news.ycombinator.com/item?id=21053034).