What Causes Dizziness And Vomiting After C-section?

a week after her second C-section (first was 16months before the second), my wife started to feel dizzy and nauseous and vomits. She can't get out of bed because she's too weak and everytime she gets up, she feels dizzy and often vomits and has headaches. It's been about 4 weeks now. Our doctor prescribed her calcium, antiobiotics, and medicines for stomach problems (pills and then injections thru perfusion). She got better for a few days (but still couldn't get out of bed) and now she feels dizzy even lying in bed and vomits and has headaches again. She's getting desperate. It's lasting too long! What's happening?