Has this ever happened to you? Suddenly HOT head, lost vision, nearly passed out

I got up this morning after a solid 12 hrs. sleep (gotta love weekends) and started washing dishes while my hubby made breakfast. I was about 5 minutes in when the side of my head facing the window started feeling extremely hot. I closed the blinds and tried to push through. Still felt like it was on fire. Suddenly my vision went dark, felt a little dizzy, and I could barely get to the sofa to lay down. I got up after a few minutes and the same thing happened again, almost blacked out. Checked my blood pressure and it was OK - 107/70 with a HR of 47. I drank some water and tried to relax.

Man, pregnancy does some weird things with hormones and blood volume! I ate some breakfast, had some caffeine (guess it helps constrict blood vessels?), and am resting horizontally. Anyone else experienced something similar? I am 10 weeks today.