Is my house making me sick?

About a week ago my partner spent the night and woke up with a different kind of headache. I've had a mild headache all week, which is rare but I figured I shouldn't have had my one bedtime beer and drank more water. I work from home - I've felt off, had trouble focusing, got tongue tied etc. He spent the night and couple nights ago and woke up with that same kind of headache. I finally figured it might be a gas leak or carbon monoxide.

I have a natural gas furnace and water heater. Neither are over 5 or 6 years old. They are located in the crawlspace. My house is 140 years old and passed inspections when I bought it less than a year ago.

I went to the crawlspace to see if maybe there was obvious backdrafting at the water heater and started getting lightheaded almost immediately so I just sat outside for a bit.

I did have my gas company come out and everything tested normal. I've hardly spent time at my house since and slept at his. He actually threw up after leaving my house (he does get anxiety pukes so that MIGHT have been it but I also felt woozy). Apparently everyone has been having a bad week though and my friend said it might be some sort of energy, but I don't really believe in that. Any ideas?