Could Headache Be Due To Tumor Or Aneurysm?

I have had a headache in the back of my head now for 8 days. It feels like where C1 and C2 are. It feels like it's a pulsating headache. Motrin helps, but not very much. I don't have any other issues except for the headache. No blurry vision, no vomiting or being nauseuos. My BP was 133/81 and P: 101. I'm scared that I might have a tumor or aneurysm, or even spinal fluid leaking into my brain. Please help!