Okay, So I have a 5 yr old son who vomits on a monthly basis. Prior to the vomiting there are no signs of stomache, nausea, anything. It's just random. This has been going on regularly since May 2009. If it happened before then it was sparingly. I've tried convincing myself that it's a stomach virus, but this is monthly, literally. Sometimes it'll last one day, other times it will last one week, and I don't know what it could be. Any thoughts as to what this could be?