What Could Cause Pulsing Headaches And Upper Back Pain That Worsen When Sitting But Improve When Lying Down Or Standing?

Yesterday night had horrible pulsing headaches that got better when I lie down and very bad when I stood up. After an hour or two of it getting more severe, pain moved into upper back. This morning the headache was mild and throughout the day got better, and is almost gone now, but feeling a little pressure and generally a little off. Back felt alright in the morning but after sitting down a while start to feel sever pain in upper back, only goes away with lying down or standing up