Thanks for your query to Health Care Magic..
I resd your concern and your symptoms of fainting
and weakness is not due to Vitamin C
, Its all due to lack of energy and main cause of fainting is due to hypotension
or can be due to Hypoglycemia
due to demand of excess energy by your body.
Have plenty of water and also energy drink will help you to fight against fainting symptoms and I suggest you to get checked for fasting blood sugar level .
Hope this information Helps you .
Thanks & Take Care..