Maybe a minor reaction to the flu shot??

What about Vitamin C ??
- we use those EmergenC packets (1000mg) that you dissolve in a glass of water and drink.
There's probably other types like it now too.

They added more sinc ethe last time I looked at their site - I usually get them at a store when I see them on sale.
-http://www.emergenc.com/index.php/products/original