Constantly ill since going back up to 10mg cit

Hi all, just passed the four month mark of 10mg cit and generally doing better. However, I’ve noticed a bit of a weird pattern, and was wondering whether anyone had experienced something similar.
I seem to keep coming down with the same ‘virus’, which is really annoying. Had it back in September, around the 19th, then about a month later in October, then for a couple of days at the beginning of December, then this weekend just gone.
I feel nauseous, wiped out, really exhausted and very shivery, like I’ve got a chill. And completely brain dead. I slept most of this weekend.
I’m wondering if it’s a virus; I work in a school, and they are very germ filled places. I’ve been really stressed this year so it could be that my immune system has taken a huge whack.
However, I’m also wondering if this could be a side effect. I noticed on the leaflet it said the cit can cause ‘flu like symptoms.’
It’s very weird and am not sure what to make of it…