Allergy to Asian Foods?

In the past year, I have eaten once at a Chinese Restaurant and once at a Japanese Restaurant. Both times, about 3 hours or so later, I threw up. They were both very similar experiences, except the last time I was sicker longer than the first, but I ate way more of the Japanese food than the Chinese. I don't get sick for days after or anything, just the little episode a few hours later and then I am fine. Could it be possible that I am allergic to something they use in there food, or did I just get contaminated food twice in a row? I don't eat Asian food all that often, and when I do I don't have a problem if its like a fast food type. I have no idea what would be the difference, but there seems to be.