Yes, flu like symptoms is a symptom of die off. It's the toxins releasing into your body and your body giving an immune response.
We have done the cleanse three times now, and it always seems to really hit after the two week mark and continues on for about a week. Not pleasant, but you know it's working! Are you drinking lots of water?
On our first cleanse, I had a fever for a few days and felt REALLY week until I passed gulgitha in the toilette! HA! So, it may just be something that is trying to come out that is taking it's time as well. Please keep going. You are almost there!