im 22, 190 lbs and 5'6". around noon i went to shadow a doctor in a teaching hospital and after standing for a couple of minutes, i stated getting hot, with blurred vision, and nauseous...i almost vomitted and had to sit down. I felt myself about to faint. the only other time i have felt this was in 2009 at work, i was also on my feet? I dont recall eating or drinking anything this morning. What could be the problem? some 4 years back after i stopped working out i had high blood pressure but its normal now. I am far-sighted and wear contacts but no other health issues other than a little overweight.