How Long Does Food Poisoning Take To Get Through The System?

I have been having diarrhea & vomiting profusely starting monday evening @7pm. Believe i ate something bad around noon that day. all through the night i was barely sleeping between vomit and liquified diarrhea. by the next day i barely was able to eat. Had a bowl of rice, some crackers, took a couple of Immune 7 capsules, and a Bio-K yogurt. felt weak with a headache all Tuesday, with still having the Diarrhea. Today Wednesday i woke up at 8 and tried a bowl of rice crispies with soya milk. threw it up a few hours later~ the milk with had a sickly sweet taste in my throat and again liquid Diarrhea ensues until now. My question is this; how long does food poisoning take to get through your system? and should i go to the Hospital?