I also had a cold that lasted 1.5 weeks after Thanksgiving, and this is incredibly rare for me. I was also taking vitamin D3, and DayQuil to make it through a few work events, though I understand that it just suppresses the symptoms, but it barely did that. It was a weird cold, but it did come after being exposed to 5 different sick households, after a tour de New England and Long Island, plus having wheat products, so who knows what shot my immune system. The weirdest thing about it was that it was not really bad, just insistent and annoying. Maybe you had some naughty foods during the holidays?