Stereo,
Sorry you have the flu!
Feel better soon - double up on your probiotics.
It is not uncommon to get the flu or a cold when starting LDN, but it usually happens within the first 72 hours as your immune sytem gets geared up.
I don't believe this would happen at week 3.
IMO, you've caught the flu, regardless of LDN.
And btw, from what I understand it is going around.
I do hope you start to feel better soon!