I don't know that a monitor would do you any good at all anyway without a full workup to see what all is going on. There's just so many things it could be. Not eating and stress together could be all it is, doesn't have to be related to your blood sugar specifically. But you do need to take time out from your studies to eat :-)

I was having trouble with nosebleeds during the time when I first took the GRE's back in 1973, and in the middle of the math portion had one. That was terrifying as I didn't feel well and I'm trying to hide it afraid they'd throw me out, etc. So I don't recommend fainting either :-)