Hi, From the data you provided, it looks like your son had anaphylaxis that is type of allergic reaction. The symptoms are due to anything that are allergic to particular individual. On my your son is having more than enough dose of vitamin C. Our body needs less than 100mg per day of vitamin C. The vitamin is replenished in our body with the raw fruits and vegetables. No need of such huge supplements. Even several medical studies also proves no benefit of high Vitamin C intake. Since the supplements are prepared using other metals as preservatives, it may cause allergy. So my advice is to avoid the synthetic supplements. Recommended daily Vitamin C can be obtained from citrus fruits and raw or slightly cooked vegetables. Take the fruits during inter meal period because there may be absorption issue with high glucose intake which are from food we take. Hope you got the thing. If you still have any doubt, question me.