At some point yesterday afternoon, physically and mentally exhausted, it occurred to me that I hadn't really had anything to drink since I woke up that morning. So I forced myself to down about half a bottle of water (12 oz or so) - and within a few minutes felt a world better. So I finished the bottle over the afternoon, big thing of kool-aid at home that night, and this morning I'm feeling better physically than I have in years. Apparently most of my regular symptoms - fatigue, sinus congestion / pressure, joint aches - are from chronic dehydration. I usually have a pretty poor sense of thirst, I don't feel thirsty so I forget to drink anything. When I do it's usually tea or soda, combine that with caffeine tabs and the diuretic effects got rid of most of what water was coming in.
So, note to self: treat water as a medication, drink it so you'll feel better!