It's gonna be okay.
It's best not to worry about it until you know for sure what it is.
It could just be that your white blood cells are high, and they need to give you some antibiotics. Or maybe something in your blood is a little high or a little low.
If it was REALLY REALLY SERIOUS, they'd want you at the doctor RIGHT NOW.
Author's response
Hopefully
YOU'RE RIGH :D