I am also like Erin- vasovagal.  Although I was numb from a shot of numbing meds I still went vasovagal.  But had absolutely no pain.  I hate that you had the same problem.  Here is more about Vasovagal syncope: 
Causes 
Vasovagal syncope occurs when the part of your nervous system that regulates heart rate and blood pressure malfunctions in response to a trigger, such as the sight of blood. Your heart rate slows, and the blood vessels in your legs widen. This allows blood to pool in your legs, which lowers your blood pressure. This drop in blood pressure and slowed heart rate quickly cause diminished blood flow to your brain, and you faint.  
Common triggers for vasovagal syncope include:  
Standing for long periods of time  
Heat exposure  
The sight of blood  
Having blood drawn  
Fear of bodily injury  
Exertion, such as straining on the toilet  
Symptoms 
Before a faint due to vasovagal syncope, you may experience some of the following signs and symptoms:  
Pale appearance to your skin  
Lightheadedness  
Nausea  
Feeling of warmth  
A cold, clammy sweat  
 Shellie