Well, I'm finally over my flu - and I'm starting to get joint pain again!
Can I explain what happened? No idea. Perhaps because I did less while I was sick I didn't stress the joints as much - although the pain stopped before the flu symptoms started and I did sneak in a bit of extra exercise in that time. Perhaps while my immune system had something legitimate to fight, it forgot to fight my body as well (I doubt there'd be any actual medical evidence to support this - but it's a nice idea. It gives a reason to appreciate the flu!)