i had a bit of an odd experience just yesterday after forgetting to turn off a gas burner that was on low in my kitchen nearby my workstation.
it could be carbon monoxide or methane/propane/butane intoxication.
check over the state of ventilation in your place if you have gas stuff in the house. and check the gas stuff.
this kind of intoxication is nasty. i messed around with it a bit in my teens huffing lighter fluid gas, and more recently played with diethylether. it sounds like it might be something of this nature.