What Is The Headache Radiating To Shoulder Along With Stiffness?

I was at the E.R. 2 days ago for head pain and/or headache. All I know is that it really hurts. It's my worst pain ever. No trauma, not carbon poisoning. It just started to hurt. The pain strays from the front of my eye, above the brow line, and stretches back to the shoulder of my right side. I feel great stiffness in this area. Along with pain when turning my head right and looking down. I am unable to bend over without excurtiating pain! I have had a CT scan and it came back clear. I have had no trauma to the head It hurts dredfully and won't stop. What is this? What should I do?