Are you drinking tap water? On one odd occasion, back when we lived in Raleigh, I had gastro-intestinal issues for about a week, much longer than virii usually last for me. I finally caught a pattern where it was being triggered when I drank tap water. Once I switched to bottled water, it cleared right up. After a few weeks it was fine to drink tap water again. ( Maybe something was blooming, or they were treating the water for something seasonal? )

It's a long shot, but that would be a lot less annoying that soy or wheat ...