When I see reports of food poisoning here I tend to have a bit of scepticism about it, since usually symptoms appear long after most people think - days rather than hours. However Bacillus cereus off reheated rice is a bit of an issue, and can lead to very bad vomiting within 6 hours. It works on not just the immune system but also on the nerve system. It's not the bacteria that's the problem, though it is capable of doubling up every 20 minutes, but the bacteria excretes a toxin (Cereulide) which survives cooking. I'm sorry to hear about this, it really sounds most unpleasant. Usually it's best to get a clinical review of your case to be sure, since there are a range of other things, including non food specific pathogens, that can cause something similar. If it was that meal then usually other cases would follow.