tfkeel

Taking my first guess, and that you had a flu virus, I think you may have picked up a secondary infection - or, diarrhea is sometimes a flu symptom itself.

There is also some diarrhea associated with antibiotics sometimes, if you were taking them with your flu.....

And, as you say, yes, food allergies are a common cause of diarrhea. But diarrhea is more often a result of infections, possibly infected food. The reason I don't jump on allergy is because you are not likely eating different foods now than you were prior to the flu.... if this is wrong, I apologize for assuming incorrectly....

If you experience this more than a week, see a doctor... you can become dehydrated easily if you have persistent diarrhea. Make sure you get plenty of fluids.