Sounds like one of those 24 hour things you get from mild food poisoning.

If you have the pukes, Ginger helps big time for nausea - even better than conventional OTC medications. I'd ask your mum or dad to pick you up some of those ginger capsules. They're pretty cheap, completely safe (it's just ginger) and natural. You can pop like three of 'em every few hours and it usually settles your stomach enough for you to keep your lunch down.

There's an episode of Mythbusters backing me up on this one! (although that was done on motion sickness)