The exact nature of Queen Elizabeth's “tummy bug” is unknown. It appears to be gastroenteritis. The symptoms of gastroenteritis are diarrhea and vomiting. Dehydration is also common.
This is the first time Queen Elizabeth has been hospitalized since 2003. That was when she had knee surgery. Queen Elizabeth, despite her age, is relatively healthy and rarely cancels appearances or trips. This is a rare occasion where her schedule has been cleared.
It is unknown if Camilla Parker-Bowles has sent Queen Elizabeth any lavender cookies to help with her stomach troubles. Camilla Parker-Bowles sent lavender cookies to Kate Middleton when she was suffering from acute morning sickness. Lavender cookies can be dangerous to pregnant women.
At the time of publication, Queen Elizabeth's stomach infection does not appear to be life-threatening. It is safe to say the she is being taken care of very well at London's King Edward VII Hospital.