I too experience Hot Flashes - I think my Doctor said it may have something to do with the Lupus -- I am in early menopause (which I heard can go 10 years - can someone PLEASE tell me this isn't so???).
The other thing that can fluctuate is your (body) temp. A lot of us have fevers on a daily basis. It is not the same as a hot flash - more like I feel like I want to put my head down and I just don't "feel" right.
Anyway, I thought I would mention both because when I'm getting a fever - it too can rise rather quickly too.