Perifedup

Sounds like either a coincidental thing that happened with a period and a possible virus or, perhaps, you may be getting a little low iron/hemoglobin wise from heavier periods. It's so hard to say over the net like this. Only your doc can run blood tests to check out your iron/hemoglobin levels etc..

Very often when we get our periods, we don't feel much like eating. Could you have skipped meals that day? A lot of us will also get that light headed, dizzy feeling with a heavier period as well.

If this keeps happening, I'd make a quick call or visit to your doc and just run it past him/her. I'm sure it's nothing much wrong but, best to be safe than sorry.
And, by the way, I used to nearly faint at times with some of my periods. I know a few girls who were like that as well. It's not all that uncommon but, if it keeps up, it does warrant running it past your doc. Heavy periods can drain you and you may need some help with supplements or perhaps, birth control pills to get the bleeding slowed down a bit if you're running low due to the heavier periods.