Our carbon monoxide detector went off, and this made us realize we had a leak. Come to find out that my room in the attic had a much higher concentration because it rises and there was no detector up there. That means I was likely inhaling it over a long period of time, which explains the abdomin and chest pains I have had for a while.

But specifically this is good because I got my own detector and was able to catch the old furnace (that we don't use) was still leaking even after it was shut off, and then I convinced our landlord to have the gas people just cap the pipes to it and rip out the whole thing. And I am already feeling so much better physically a week later!