In Which I Learn Some Health Stats

I've been extraordinarily exhausted lately even when I get what should be sufficient sleep. After that went on for a few weeks, when I didn't really have time to be sleeping at all, I went to health services on campus. The doctor suggested that I was just stressed out. When I tried to tell her that I know stress, hang out with it every day, and this is not stress, she seemed skeptical at best but took some blood. All the tests came back negative. She again suggested stress; I again reiterated that if this was how my body reacted to stress, I'd know it by now. She said there were some tests for rarer conditions that she could run. Those rarer conditions? HIV and ... mono. Now, I assured her that HIV seemed highly unlikely (considering...), but why in the world would she wait until the second blood test to test for mono? The tests haven't come back yet, so I don't know whether I have mono or not, but I'm just saying that, in the scheme of things, when a student comes to the doctor complaining of extreme fatigue, shouldn't mono be up there at the top of the list? And is a USC student really just as likely to have mono as HIV?