Long story short I have apparently been getting low level chronic carbon monoxide poisoning for potentially up to 4 years. Our gas water heater flue was busted open, and gasses weren't venting outside. Instead every single time it heated it spilled CO and CO2 into the finished basement where I live and work. The pipe was corroded and pitted, and the rubber nearby was partially MELTED. I work about 10 feet from it.

Fortunately it was not high enough concentration to just straight up kill me, but it explains why I've had so many seemingly unconnected and sourceless problems for the last few years. We have a new electric water heater, and I feel like I can actually breathe for the first time in ages.

It will take time for it all to fully go away, but I'm hoping the headaches, shortness of breath, confusion, memory problems, phantom movements in the corners of my eyes, and more all go away. It makes so much more sense now. I'm frustrated it took our water heater rusting out and starting to leak for anyone to notice the problem, but at least the problem has been fixed.

So let this be a warning to you all. Get your hvac and water heaters checked regularly.