My thoughts + IMPORTANT Vit C information

It could be a healing reaction but it sounds unlikely! It could possibly be the acidic route but I haven't heard of people vomiting because of a upset stomach unless its food poisoning but not pain from acid. It might be your allergic to ascorbic acid or something in the product you bought. Did you buy this same vitamin C brand? Seems like the Ester C might have cured the problem anyhow. I use mega dosage Ascorbic powder and Im fine luckily :-)

Please Monitor your Zinc and especially Copper levels as Vitamin C in large dosages depletes these quite quickly. Great if you levels are already high but if they are low then you need to increase Zinc and Copper. One of the first signs of copper deficiency is conjunctivitis (chronic) normally in the right eye. Also increase intakes of Calcium (w/ Vit D, Boron, Magnesium), Manganese and Vitamin E as these are all depleted by Vitamin C

Take some Alpha Lipoic Acid which recycles the Vitamin C keeping the dosage more consistant for longer periods of time.