When I had a cold on P1, I did a cold pill and sugar-free cough drops. Vicks vapor rub might be a good non-systemic way to manage also.
For the stomach flu, I think you do the best you can. If you are really dealing a serious flu, a few saltines shouldn't hurt you....you can always skip your restricted pack since the carbs values wouldn't be too different. Hope you feel better soon!
"Comparison is the thief of joy." - Theodore Roosevelt