Twinkle, have you ever tried taking vitamin B? I used to get so down when it was my time of the month, I would cry like clockwork. Even tho I knew it was down to the time of the month I couldn't force a smile.
My mum (a medical herbalist) suggested I try taking some vitamin B (a combined tablet with all the B's including B6 in it). I have been taking them everyday for months now, and havn't shed a tear when the time approcahes. It might be the placebo effect, but it worked for me.
In the meantime grab a spoon, some skinny cow ice-cream and scoff the whole tub.
Hope you feel better soon. x