Apparently I have fermented my gut some of the time most of my life. This is the deal where the yeast grows in the upper gut, which is supposed to be more or less bacteria and yeast free. A very common, and under diagnosed problem that causes one of the many types of chronic fatigue. I have gum disease, so perhaps that makes more prone to do this.
A very long time ago I did some strong antibiotics for impacted wisdom teeth, but I really think the problem pre dated that. It was not a bad case, just the "normal" get some heartburn if I ate a huge serving of pizza type of thing. Also mild but short lived fatigue from time to time. All very vague symptoms, nothing that would even slow me down much at 30. Even during a fatigue period, back then I'd still go climb a huge mountain to ski down it. This type of chronic fatigue IMO, is best gotten rid of by working harder. Metabolize out the poisons in your blood that much quicker. Burn that bad alcohol out. Ever "worked off" a hangover? Same thing. A full liver has no place to put excess blood alcohol. So empty it.
But that was then, before West Nile Virus gave me encephalitis, and gave me the REAL DEAL, post viral fatigue. Now with my metabolism crippled, a short walk could result in a complete bonk similar to those athletes you see flopping around after an ironman triathlon. Literally, a two mile walk became for me, equal to a triathlon. Then for three days of recovery, anything I would eat could not digest. Many of my organs could not function right until my ATP levels recovered. Food would just lay there in my stomach and gut till it fermented instead of digesting normally. This meant the few yeasts I tend to carry got a huge boost. If you digest abnormally slow, you likely are having some fermenting gut.
So then I had a severe case of chronic fatigue making my previously very mild fermenting gut fatigue 100 times worse. A real death spiral, and at that time I was expecting to live only a few more years, and no doctor was helping me for shit.
On the bright side, a very good English doctor has the diet for post viral fatigue figured out. She's the one that touts the paleo on her website, which saved my life. This was for me, for my problems, the only diet that would help me. Again, I'm no longer on pure paleo at all now. If I'm careful, I don't encourage the yeast to bloom. I understand what is going on now, and when to quit the carbs again for a few weeks if I start to feel that hungover feeling.
I don't need the paleo as much now, because some other things I have done sped up my recovery from the post viral fatigue. So I don't do those mega bonks anymore. Now I support my ATP with lots of creatine, so I never dip into my reserves of ADP. As long as I stay in oxidative metabolism, I don't bonk and shut down my pancreas, liver, intestines for three days anymore. Those bonks, they were killing me. Oxidative is using your ATP, converting it to ADP, and then creatine helps your convert it quickly back to ATP. But if you need it, your body will just burn up your ADP, and then it takes three days to make a new supply. Till then, you are barely alive. I forget who now, but somebody on ES suggested the creatine. It really helped! Now if only doctors would learn this!
At this point, I'm having a better summer than any in the last 4 years, and I can do anything I want normally, provided I don't push myself too hard. I just can't do an 8 hour shift of hard work. But I can do 8 hours of easier stuff, or hard work with lots of long breaks now. I'm still suffering from post viral fatigue, causing low production of ATP, but If I'm careful, I can avoid the bonks completely now. Eventually, less bonking definitely speeds recovery. That's why the not as smart US doctors say the only cure for post viral fatigue is to quit working. That's still step one of recovering, but far from all of it. In Europe, they have a much better handle on this problem.