What Causes Acute Headaches, Weakness, Sickness, Dizziness And Lightheadedness?

Been getting bad headaches on and off now for about 6 months. Lately they have returned. Causing me to feel weak, sick, dizzy and light headed. Whenever I have seen my GP, I have just been told its normal headaches or a virus. Surely not all headaches can just be this. I worried its something more serious. What can I do?