Extreme stressful situation or someone internalising external pain can lead to fainting or syncopal episode due to Vagal n shut down. An eeg can sometimes differentiate between the two.
Next Steps
See a psychiatrist to do a detailed work up.
Health Tips
Breathing in a brown bag or your fist and resting your head on a table below your shoulders can increase the blood flow to head. Talking to a psychologist can also help.