Sorry for the late reply...thanks, everyone. I've been feeling ok otherwise, and I'm not on any medication...exams could be considered stressful, but I've done plenty of them before...weight hasn't changed recently (I've been trying to lose some of the 8-10lb I gained since coming to uni last year, but it hasn't been working - I'm 123lb, at 5'5). If it hasn't come back by the end of May, though, I'll see if I can get a doctor's appointment then.