Thanks for writing your query.
It will be helpful if you give more information on :-
1. Are you diabetic?
2. Your blood pressure readings.
3. Any history of medicine intake?
It might be a possibility that you had an attack of vasovagal syndrome. It can occur due to decreased supply of blood to the brain.
You should get your blood pressure monitored.
You should also get yourself investigated for :-
1. Head scan
2. Blood sugar levels
I would suggest that you should get yourself examined by a Neurophysician.
Whenever you feel that you are going to develop an attack, lie down with head end lower.
I hope this is helpful to you.