why do i have stomach flu?

1/ drinking soya bean packet drink which has been left in the car to warm up in the afternoon. perhaps some cockroaches decided to bathe inside too... BLEH
2/ eating too much in a short time interval.
ate dumplings at 0630
ate nasi sambal goreng at 0930
ate mixed vegetable rice + soya bean drink at 1230
ate a very creamy blueberry bun at 1730
after all these i did not eat anything until 10 this morning.
3/ sleeping immediately after eating lunch on a reclinable chair
4/ taking in big breaths when passing by the rubbish dump area and saying 'very nice smell!' before taking in another 2 litres of rubbish air.
5/ getting in and out of the car during a very warm day.

in i think i am suffering from indigestion too. was trying to puke all the food out yesterday however to no avail. the valve in the throat just wouldn't give way. i know i am VERY hungry now but i have no appetite...luckily the fever had already subsided...but i can't work tonight...i am very sorry to the person who had to report for work today to cover me despite having applied for leave himself/herself.