A sinus infection is bacterial. Influenza is viral. I'm not sure how the two could be related, unless your weakened immune system allowed the second and completely unrelated sickness in?

Correlation is not causation. I have never broken a bone. Doesn't mean that if I break one next Tuesday, Tuesdays cause broken bones. Do you eat enough fat for your body to use all the D you take? Do you also summlement with k? And honestly, why on earth did you feel it necessary to megadose like that? I'm honestly just curious.