Then, if you already have stomach flu, then I don't see how bleaching your clothes might help here. Take a medicine.
Finally, reading about stomach flu (I'm not a doctor), it doesn't look like a serious problem: > Most people with the stomach flu require no formal treatment. The key to a rapid and safe recovery at home (home remedy) is proper hydration.
If it gets more serious then take a pill or/and go to a doctor.