What Causes Severe Headaches, Neck Pain And Dizziness?

I am awaiting surgery for a hysterectomy due to fibroids, heavy bleeding etc. which has caused me to have anemia problems. I am taking iron tablets and b12. Two days ago I began having severe headaches, very much pain in the back of my neck and dizziness to the point I nearly fainted in the supermarket which lasted several minutes. I don't know if the two are related but this is now reoccuring daily