Hi Beste, MOST of people flying with flu won't have major problems.
But you can take extra precautions.
I did fly last December with FLU, I just got Guaifenesin couple of hours before the flight, it's a descongestant and I found it on Internet others used it also when flying. Try to use earplugs, but the ones for airplanes, not only because of pressure, but because some airplanes are loud, not loud enough to cause you damage, but if you feel your ears kind of sensible the sound could bother or irritate you.
And the best, just relax, everything will be ok.
Regards!