Sorry to hear you aren't feeling that well Michele.
Normally, if it's food poisoning, more than one person will start to feel ill, and it can take anywhere from 6 hours and up.
There is only one theory I have. I no longer to go chinese buffets(much less chinese restaurants) because they cut the meat into large chunks and are often not well done. I normally get a little nauseated afterwards and it can last for hours.
Your stomach could be sensitive to certain types of food and you may not know it. Have you had this problem before with seafood? You just have to be careful with seafood to begin with. Could you be allergic to it?