Swollen Throat Glands And Pressure In Head When Lying Down...seems

Swollen throat glands and pressure in head when lying down...seems to drain when standing or sitting upright propped up against a few pillows...have to sleep sitting up...started a few weeks ago with just the head pressure when lying down...otherwise almost never sick, but often told by doctors that I was dehydrated, even though I never felt it...female 56 years old...5 ft. 4 in. approximately 127 lbs. - recent rapid gain of around 10 to 12 lbs.