My daughter(15) has a slight fever that keeps going up and down. I'm worried it might be serious.

First it was 99.0 then
99.4
then
98.7
then
99.3
then
99.5
then
99.7
99.8
in the morning:
98.4
and now it's back up to 99.4

And I know how to get AIDS.
Semen (not me)
Vaginal Secretions (not me)
Breastmilk (not me)
Blood or blood products (not me)
tatoos (never)
peircings (once)

Those are the only fluids. Never did any of em, and my daughter hasn't either. except the piercings, but that's only if the person who did it got blood in you, and they used some maching that didn't.

She was complaining about her sinuses were stuffed up. She's had drainage and a few times today a sore throat. (possibly from drainiage?) Could this be a sinus infection?

Is this bad? Or could it just be some sort of flu virus?
I'm concerned that it could be HIV, but I'm a hypocondriac, so, please let me know as soon as possible!

Sure, someone's gonna reply but who and when? I need the info now!!!

ps can a fever like this develop with anxiety?