Yes this change inSdowner,
Yes this change in your diet back to unhealthy foods can make you feel very sick. Your body had become clean and was getting lots of nutrition. Then that abruptly stopped. Once it is clean it doesn't like a regular diet of junk any longer. The unhealthy foods are just that unhealthy in that they contain toxins and the body works hard to get rid of them and they are not just absent in nutrition they are nutrient thieves robbing precious nutrient stores from your body. An occasional treat it can handle but more and it revolts.
You could have also been exposed to a virus or bacteria that is making you ill, however my bet is the change in diet is the reason you feel badly.
Start incorporating healthy foods back into your diet. The NB makes that easy on your body.
Wally Bishop C.N.C.