Re: is this a flu?
No, that's not the flu....the flu (influenza) is a respiratory illness. You have obviously ingested a bug through means of hand to mouth, or possibly in food from someone's improperly washed hands after going to the bathroom. That's usually how it's spread.
It's almost impossible to avoid illnesses like that when its spread is quick, especially in a school, daycare, senior home...etc.
Proper hand washing with soap between all the fingers and nails and rinsing for 15 seconds is said to be the best way to help from keeping it from spreading. Kids are notorious for eliminating that part of the bathroom process. Keeping fingers from one's mouth also helps. I worked in a school, and it took the first year to finally figure that out.
One thing that you may want to consider is taking acidophillus with bifidus. I use Webber brand..cheap and it works. It keeps the bowel flora balanced, especially during and after a gastro attack.
Feel better soon.
It's all a matter of perspective!