What Causes Severe Headaches Along With Nausea And Sensitivity To Light?

I am very concerned about these headaches I started having approx. 3 months ago!! They started slow, yet now they are debilitating!!!! I stay nauseous and the pain in my head is too much!!!! I cannot be around light very much at all!! I no longer read, nor am able to stare at computer, phone or, Tv!!! Can you recommend any helpful info.? Thanks: Sherrie