I had a vomitting bug 6 times during my pg with Tom (DS2). Most times it lasted 24 hours. The last time it lasted for 4 days and I ended up in hossy on drip. As long as you are not dehydrated there is no need to worry. If you are not urinating or otherwise feel dehydrated, see a doctor straight away, or call your mw/ob who will probably recommend hossy. Otherwise don't worry. Not once was my ob concerned about my lack of food intake, it was only the fluids that worried them.