This Smell

For some strange reason, today I have been smelling this smell.. almost like exhaust from a car and at time gas and its making me kinda sick.. Im at my patients house on the 3rd floor. She doesnt smell it and she thinks I am crazy. I know that sometimes when you are low on something your body will "crave" a certain food to replenish it.. does it work that way will smell? What the hell could I be low in when I smell gas and exhaust? I mean.. I need gas in my car but I dont think that works fmthat way..lol