I HAVE HAD SURGERY ON THE MIDDLE BACK OF MY HEAD FOR A CYST (3 TIMES). 1ST TIME LASTED 8 YRS, 2ND TIME 2 YRS, 3RD AND PRESENT 2YRS, BUT NOW I CAN HEAR IT BUILDING AGAIN. IF I SLEEP WITH MY HEAD LEANING BACK, I BELEIVE MY NECK FILLS WITH FLUID. WHEN I AM WAKING UP I CAN HEAR THAT FLUID MOVE UP TO THE SPOT IN THE BACK OF MY HEAD. SOUNDS LIKE FLUID BEING SHOT FROM A WATER PISTOL. SO FAR THE DOCTORS THINK IM CRAZY, BUT BEFORE LONG I WILL NEED SURGERY AGAIN, BECAUSE OF THE PAIN AFTER IT BUILDS UP.