Yes, I have that sometimes on one side and sometimes on the other (and sometimes on both sides). It sounds like sinus headache based both on the location and the change in position causing it to get worse. Tension headaches tend to be behind the ears, around the temples, and across the back and top of the head, while sinus headaches tend to be closer to the eyes and forehead, but I find that they sometimes are hard to tell apart and for me at least they can even happen simultaneously (tension and sinus together). A migraine headache is very different and easy to tell from tension or sinus headaches. An eyestrain headache can also happen around/behind the eyes, but the positional thing again sounds more like sinus headache to me. Changing position by sitting up or standing up can suddenly change pressure in your sinuses, and makes the headache appear worse. Leaning forward can do the same thing sometimes.