Thank you for writing in today.
Exhaust does present with some potentially harmful side effects when inhaled. At this point, since you had prolonged exposure and currently demonstrate symptoms of nausea and headache, you should be evaluated. Possible carbon monoxide poisoning should be ruled out. This involves a blood test. Also, in addition to a full physical, your oxygen status should be assessed. When carbon monoxide enters the blood, it changes the way that the red blood cell carries oxygen. This can cause a person to be hypoxic, which can manifest as nausea and headache.
I realize that no one wants the "go to your provider" answer; however, sometimes it is necessary.