Feeling dizzy, no energy, etc. anyone?

Kk
Yesterday and today I can barely get out of bed. I feel like I have no energy. When I stand I feel dizzy and like I need to lay back down right away. 
I'm carrying twins which I know is way more work for my body, but I've started taking iron which was recommended by my doctor (I read iron deficiency is sometime the problem for these kinds of symptoms). 
Has anybody else been feeling this way?