If you have a slight annoyance somewhere in the throat or neck area your brain can become slightly irritated and is very sensitive to changes in blood pressure. When you stand up, your blood pressure goes down. Some medications can cause similar symptoms. If the pain continues for 2 days, you should probably contact your doctor.
I think of low blood pressure gravity pushing blood pressure to your lower extremites. My suggestion not to move so radpidly when changing positions. Seek medical help if this continues.
This pain is probably just related to blood rushing out of your brain when you stand up. Gravity bring the blood down if you stand up too fast. The best thing to do is actually just take your time standing up and not go as fast. If you are really worried, you should ask your doctor.