What Causes Severe Pain In Head And Neck?

I have had the worst headache ever for two days now. I have diabetic and high blood pressure. I take meds for both. My whole head and neck hurt so bad. I took 4 Advil and had no relief at all. I ve tried heating pad on my neck and ice packs. What else can I do? I feel like my head is going to explode. I checked my blood pressure, it was high so I took an extra enalapril. Still no relief.